How experts are helping break the expert evidence logjam

The logjam is between the view of experts and their evidence as held by the legal community and the view as held by experts themselves – one negative and not so well founded and the other positive and more evidence-based.  Experts are breaking the logjam by speaking out, telling it like it is not how the court perceives it to be.

We should all read Ruth M. Corbin’s excellent paper, Breaking the Expert Evidence Logjam: Experts Weigh In, and some of the 65 citations, on the disconnect between the court’s perceptions of experts and the views of the experts themselves. (Ref. 1)  It’s interesting, and surely embarrassing, that the court’s views are not so evidence-based.

Read the themes and gaps in perception that Dr. Corbin found in a pilot study:

  • that included 152 experts who have testified in Canada – that’s a lot
  • then reflect on the cause of this disconnect – I’ve got my views
  • see ideas for fixing the problem that resonate with courts and experts alike, and,
  • read Ruth’s call for additional, more quantitative studies to firm up her findings.

I heard Ruth present her paper at the recent Expert Witness Forum East in Toronto on February 27 and read and studied it three times since.  Its well written – no technical and legal jargon here – and a good and informative read.  You can Google the paper’s title and her name.

The Paper’s Abstract

The paper’s Abstract is a good introduction (I took some liberties with Ruth’s abstract and broke it up into more paragraphs, and commented here and there.  I also tabulated the future steps):

    “Expert evidence is perceived by many as inherently suspect.  Effort world wide is being directed to improving the process by which valid and reliable expert evidence is delivered to triers of fact.  Curiously, experts’ input on process improvements has not been solicited. (That’s quite a revelation in my view!)  One is struck by the paradox that experts continue to publicly acknowledge an expert’s duty to the court and continue to swear oaths to that effect, and courts continue to disbelieve them.  Even with the wave of new rules about expert testimony in dozens of jurisdictions, the perception of a problem has not gone away.

“A research project was carried out among a broad range of Canadian experts (and a good sample size at 152) to identify gaps, if any, between the perceptions of experts and courts…….Five compelling themes emerged from the research (and six gaps between the views of experts and legal people), highlighting ambiguities and inconsistencies in interpretation of the expert’s duty.

“The paper concludes with opportunities for next steps in three domains:

  1. Empirical research to strengthen the evidence-based foundation of future policy
  2. Economical modeling to complement the Supreme Court’s call for a “cost-benefit” analysis of expert testimony (I believe, based on my experience in Atlantic Canada, that this modelling and analysis must include an identification of principles governing the cost control of civil litigation involving experts), and,
  3. Practical steps toward creating a forum for direct communication between experts and courts (The duties of the middle man in the process, the advocate, have got to be modified a little)”   

Compelling Themes From Experts’ Comments

The five themes presented below are those topics most frequently identified by content analysis of written and interview-recorded input from the 152 experts.  Content analysis is the objective categorization of descriptive text into common themes.  There’s in-depth comment on each of the themes in the paper:

  1. Duty to the court is universally acknowledged.  The concept, or even the explicit phrase, “duty to the court”, was universally acknowledged by the experts.  No one thought otherwise.
  2. Mis-perception of motives,  ”It’s not about the money”, volunteered many experts.  They rejected this view that experts are motivated by money, that they’ll say whatever in court to maintain a revenue stream.  The most frequent motive expressed was the interest and challenge of solving difficult problems for which their expertise was needed and valued.
  3. Mixed signals from the courts: Independence, neutrality and opining on the ultimate issue.  Duty to the court was understood to entail principles of independence, objectivity and refraining from opinion on the ultimate issue.  However, experts who looked to court decisions found these principles to be ambiguously interpreted.
  4. Risky surrogates of credibility and common sense.  Experts acknowledged that they had seen opposing experts take what they considered biased positions.  “Rogue” experts may have the charisma and comportment to have their opinions preferred by the courts, to cause judges to make errors in evaluating scientific evidence, based on “common sense”.
  5. Appealing alternatives to adverse testimony with cautionary words.  It was widely observed that malfeasance should not be automatically presumed when experts disagree on interpretation of the same facts:  Collegial debates are endemic to academic life and professional forums.  Consistent with that view, hot-tubbing was met with widespread support among those whose views were canvassed.

Gaps in Perspective Between Law Professionals and Experts

Ruth’s paper tabulates the discovered gaps between published decisions and legal commentaries, and experts’ own views sourced in the course of the research presented in her paper.  The gaps are identified based on qualitative content analysis.  The differences in the published principle or presumption of the court and the compelling themes from the experts highlight the gaps for each of the following issues:

  1. Objective value of the expert’s evidence.                                                           Gap: Experts are conscious of their duty of objectivity contrary to how the courts perceive them
  2. Independence and objectivity.                                                                               Gap: Similar to previous.  Part of the problem is the court’s own confusion interpreting these terms.  Experts know what they mean; it’s interesting that courts don’t
  3. Assessment of an expert’s credibility.                                                                 Gap: Charisma and comportment in court are trumping scientific evidence
  4. Common sense standard.                                                                                   Gap: It plays a part in court but an understanding of what it is varies.  It should not override science, regardless of what it is
  5. Motives of experts.                                                                                               Gap: Experts are driven more by curiosity and solving a problem than by money
  6. Alternatives to adversarial evidence.                                                                     No gap here; a meeting of minds on reducing adversarial testimony with techniques like hot-tubbing. (Ref. 2)  This is the consensus-building north not the adversarial south


There is a logjam but the experts are helping to break it with objective comment and Ruth’s evidenced-based help.  The jam doesn’t reflect well on the court’s too subjective, confused assessment of issues at times and their susceptibility to undue influence from understandably biased players in the judicial process.

The experts are unjustifiably getting the short end of the stick in the process – perceived badly – but 152 experts can’t be wrong.  Their near universal understanding of objectivity, independence, what it means to swear an oath, and that they serve the court – no one else – is clear to the experts.  Less than 10% of experts have been found in rulings and comment to be biased.  What part of this understanding doesn’t the court understand?

The court’s perception of the expert is filtered through the advocate who presents everything from the expert to reflect best on their client, as s/he must.  The opposing advocate does the same.  The big picture is confusing and messy to the judge, particularly if it’s a scientific issue, and the expert is at the centre of it.  What’s a poor judge to do?  No wonder they have a jaundiced view of the expert.

But, Ruth’s research is setting the record straight with evidence-based data from experts, and hopefully more to come from bigger, more quantitative studies.  A judge need only read, listen and learn from the objective experts because we tell it like it is..


(A lot of the above has been taken from Dr. Corbin’s paper as I understood it.  Her paper on the hot-tub alternative to adversarial expert evidence is also very informative.  See Ref. 2 below)


  1. Corbin, Ruth M., Chair, Corbin Partners Inc. and Adjunct Professor, Osgoode Hall School, Toronto, Breaking the Expert Evidence Logjam: Experts Weigh In, presented at Expert Witness Forum East, Toronto, February, 2018 (Google it)
  2. Corbin, Ruth M., The Hot-Tub Alternative to Adversarial Expert Evidence, The Advocates’ Journal, Spring 2014. (You can Google it too)


Are experts being broadsided by bias, unbeknownst to them?

You might wonder, how is it possible for experts to avoid bias when there are so many, like dozens?  Google “bias” and see what I mean.  I saw one link where the dozens were categorized under the letters of the alphabet.  Fortunately, it’s possible to do something about bias by learning about the key ones that can trip us up.

Speakers at the recent Expert Witness Forum East in Toronto identified categories of bias that experts must be alert to.  I was surprised by the number and the fact that some bordered on deliberate. (Ref. 1)

Experts must get familiar with the ones that can show up in our investigations and evidence.  This is a first step in rooting it out of our work, and not being broadsided by a peer review, a rebuttal report or a cross-examination.  It won’t matter to those few given to deliberate bias.  But there are the rest of us, the great majority.

Two presentations on the first day of the Forum introduced us to implicit bias.  Initially with a talk on Addressing Implicit Bias On and Off the Stand (Ref. 2) and then with an Interactive Session. (Ref. 3)

Dealing with implicit bias

The interactive session made it clear that in dealing with implicit bias we must:

  1. Understand implicit bias
  2. Identify implicit biases
  3. Reduce the influence of bias
  4. Mitigate for the bias of the audience

Categories of bias in expert evidence

A presentation on the second day of the Expert Forum identified eight (8) categories of bias in expert evidence: (Ref. 4)

  1. Selection bias (Hired guns)
  2. Association bias (Advocacy)
  3. Professional bias (Self-interest)
  4. Data bias (Collection/Analysis/Availability)
  5. Hindsight bias (Preventable outcome)
  6. Noble cause distortion bias (Societal good)
  7. Expectation bias (Anchoring)
  8. Confirmation bias (Tunnel vision)

The speaker then went on to focus on the last two in the list and elaborated as follows:

Expectation Bias (Anchoring)

  • The focus is on a particular observation/theory/information provided during early stages of investigation that prematurely predicts outcome and thus influences methodology and future decisions
  • Behavioural sciences show that human judgement is powerfully affected by how problems are initially framed since humans are known by nature to unconsciously anchor on details they are initially given
  • Requires additional experience beyond the first engagement with a lawyer, which can frame one’s thinking and becomes their frame of reference
  • Inexperienced experts may not recognize when “relevant facts” are in the eyes of the client or litigator.  The expert should request all facts be made available, particularly submissions from opponents

Confirmation Bias (“Tunnel Vision”)

  • A most insidious, subconscious tendency of those desiring a particular outcome to search for supporing evidence and/or ignoring or reinterpreting contradictory information
  • Often develops from Expectation Bias (Anchoring)
  • Scientists and engineers favour report findings consistent with their prior beliefs and expertise
  • Confirmation bias requires a theory, goal or outcome to generate an attraction for bias

Examples of bias in Nova Scotia

Public examples

Expectation bias and Confirmation bias figured in the forensic investigation of the fatal accident of Janice Johnson in Nova Scotia that resulted in her husband, Clayton Johnson, going to jail for five years falsely accused of murdering her. (Ref. 4) The case was described in the presentation along with two others elsewhere in Canada, one a murder that was disguised as a suicide and another, a car accident.  I gathered from the presentation that expectation bias and confirmation bias figured in the faulty investigation of the latter two as well.

Personal examples

I have my own examples of bias in civil litigation.  One, a visual assessment of slope stability from the comfort of the investigator’s car, disparagingly called “a drive-by” evaluation in the real estate business and against some of their regulations.  And another, a critical assessment of the soil conditions at a site without a site visit.  I peer reviewed the technical reports on both these cases.

It was easy to conclude the “drive-by” type assessment at the one site because the poor construction and unstable slope were there to be seen by walking across and down the slope, particularly at the toe.  The slope was actually dangerous to walk across at the bottom.  The wording of the report exhibited Professional Bias (Self Interest), with an eye to the next forensic commission.

My second site was easy too because even non-technical people know you can’t define a surface properly with two points – simple high school geometry – and that would have been obvious with a site visit.  How do I know there wasn’t a site visit?  Because it wasn’t mentioned in the report I reviewed.  It’s an important task that would have been reported in detail in an expert’s report.


Getting familiar with bias will increase the chances that your case – expert and civil litigation lawyer alike – is not broadsided by peer review, rebuttal or cross-examination.  You can’t sabotage the dozens of different types of bias but you can learn about the few that creep into forensic work.

(Note: The numbered and bulleted lists in my blog were taken directly from the references)


  1. Jorden, Eric E., Expert witness forum looks at bias and other touchy subjects in forensic work.  Posted March 6, 2018
  2. Virji, Aly, Staff Sergeant and Moosi, S. Ali, Constable, Toronto Police Service, Addressing Implicit Bias On and Off the Stand, 3rd Annual Expert Witness Forum East, Toronto, February 27, 2018
  3. Duncan, Peter, Instructor, Toronto Police Service, Addressing Implicit Bias: Interactive Session, 3rd Annual Expert Witness Forum East, Toronto, February 27, 2018
  4. Perovic, Doug, Professor, Materials Science and Engineering, University of Toronto, Raftery, Barry, Forensic Engineer, Raftery Engineering Investigations and Lockyer, James, Lawyer, Lockyer Campbell Posner, Mock Trial, 3rd Annual Expert Witness Forum East, Toronto, February 28, 2018

“Hot-tubbing” experts reduce cost of civil litigation and ensure objectivity

One of the speakers at the recent Expert Witness Forum in Toronto, Dr. Ruth M. Corbin, referred me to a detailed description of the “hot-tub” method of dispute resolution that she had written. (Ref. 1, see also 2)  “Hot-tubbing” is legal jargon for a concurrent expert evidence process, and apt jargon at that.  Experts for all parties to a dispute get together in a court room and talk it out.  The method reduces court time and civil litigation costs involving experts, and increases objectivity.

Australia, where it originated, New Zealand, Britain and Canada are relying on the process more and more.  Other countries are taking an interest.  Adversarial America?  Not so much.

The method involves experts, with their individual forensic reports for different parties, meeting together in court before a judge and agreeing on a single expert report on the problem.  There is also a variant of the “hot-tub” process suited to other forms of dispute resolution outside a court.  This would be like a pre-trial conference and is usually in the absence of lawyers.

Seeing as more than 90% of disputes are settled out of court, and close to 100% for some types of problems, there is lots of opportunity for this method to resolve disputes.  Interest in a variant of “hot-tubing” is certain to increase in light of the Jordan decision by the Supreme Court of Canada last year.  The decision will further delay the hearing of civil litigation cases in court, at least in the short term.

To me, “hot-tubbing” is little more than a consensus-building process.  Experts do their individual forensic investigations, analyse the data, draw conclusions and formulate an opinion.  They then sit down together, peer review each other’s work, discuss the issues and reach a consensus on the cause of the problem.  Expert’s just want to solve the problem, explain the issues in simple language and get onto the next problem, particularly technical experts.  Most of us are not adversarial by nature, nor hired guns by a long shot.

Ruth’s paper is a good read in plain English with practical descriptions and examples of “hot-tubbing” in action.  The guidance and comment in her paper gets you almost to the point where you just might be able to do it yourself.  If not enough guidance, you can review any number of the 73 references and citations Ruth includes in her paper.

The “hot-tub” method is well developed in relying on the consensus building nature of experts.  But it’s not perfect as Ruth points out in three different ways.  One embarrassing defect is that development of the “hot-tub” method – to reconcile differences among experts – had little input from experts!

I can’t help but wonder if the cause of some of the civil litigation that is being resolved by “hot-tubbing” is because experts were not involved in the merit assessment stage of the cases, another embarrassment.  We get retained months or years after a case is taken and after the cost of the technical expert’s work is estimated by a non-technical person.

The omission of input by experts in development of the “hot-tub” method is recognized by people like Ruth M. Corbin and will be corrected over time.  Possibly this will be reflected at the merit assessment stage of a case and further reduce the load on the court system.

(Some of the comment in the above is taken from Dr. Corbin’s paper)


  1. Corbin, Ruth M., The Hot-tub Alternative to Adversarial Expert Evidence, The Advocates Journal, Spring, 2014 (Dr. Corbin is Chair, Corbin Partners Inc., Ontario)
  2. Biased experts cured with a soak in the “hot tub”, posted January 31, 2017





Expert witness forum looks at bias and other touchy subjects in forensic work

I attended an expert witness conference in Toronto last week and it was very good.  I’ve attended these types of conferences in the US in the past and they were also good.  But Toronto was different in its Canadian flavour and in addressing touchy subjects like bias in expert investigating and reporting, “dirty” experts and retaining experts on contingency.

I’m not so sure about the prevalence of these problems down east but in my invited talk on Principles Governing the Cost Control of Civil Litigation Involving Experts I touched on problems we do have.  Like experts retained many many months or years after a case is taken and technical investigation budgets estimated by non-technical people.

The two and a half day, 3rd Annual Expert Witness Forum East organized by The Canadian Institute, Toronto, looked in depth at:

  • Implicit bias as seen by three Toronto police officers, and,
  • Expert report writing as outlined by an experienced forensic engineer.

There was also good coverage of related topics like:

  • Case law and updates to the Rules of Civil Procedure
  • Breaking the logjam between experts and judges
  • Trends in expert witness testimony
  • Matching expertise to your case and,
  • Principles governing the cost control of civil litigation involving experts

The treatment of implicit bias was an eye-opener.  We’re human and it’s going to happen, it’s not always intended, but sometimes it’s deliberate.

Two of my daughters were interested in the conference program as well; I suspect because of the bias theme.  One is in hospital management in Toronto, and the other in veterinary medicine in the US who actually expressed some interest in attending.  So, wide appeal for the forum.

I took copious notes and hope to report in more depth on the conference but think I’ll wait on receipt of the speaker’s papers to be sure I get it right.  Particularly that on bias and report writing.  These views need to be got out there to all involved in expert witnessing on both sides of the table.

There’s an Expert Witness Forum West, and a Forum East which I attended.  There’s an argument for an Expert Witness Forum Way Down East.

I noticed some quite different practices being talked about in Toronto.  We know about bias and it was good to air it – for sure the situation is similar down east.  But the suggestion about retaining an expert on contingency even if under contract was a shocker.  Perception-is-everything would be the Achilles’ heel for that idea.

I think reference to ”dirty” experts is an unfair misnomer for “consulting” experts, a valuable and less expensive role for an expert in civil litigation compared to testifying expert.  Experts down east for the most part are objective in their investigative work and when advising an advocate for an injured party.  The most they can be faulted for is advocating for their findings.




Embarrassing defects in a building designed by architects and engineers

I’m going to tell you about defects in a building designed by architects and engineers.  Defects that should not have occurred and might have resulted in civil litigation in another time and place.

I don’t know whether to feel delighted or embarrassed on finding defects in an addition to a building constructed while I was at the University of New Brunswick (UNB).  I was in the building last fall for a reunion of my engineering class.

I pick delighted because I know that failures occur and finding them reminds us we can’t be too diligent and thorough in our work.  Even well educated, trained and experienced planners, architects, engineers and builders.  We got to be ever-vigilant that we don’t drop the ball in the face of tight budgets and schedules.

Failure occurs when a component of a building or civil engineering structure doesn’t function as it should, has a defect, or collapses completely.

1st Defect

I noticed the first defect years ago when I was studying at UNB.  Construction of an addition undermined the foundations of an existing building causing the foundations to settle and the brick wall in a classroom to crack. (see Appendix) You could see daylight through the 1″ crack (it’s been caulked since).

Cause of 1st defect

The undermining causing the crack was due to the technique used during construction of the foundations to the addition.  The technique is well known, including it’s limitations that must be taken into account. (see Appendix) If not, foundations are undermined and cracks appear in brick walls.  Or worse. (see pictures of a catastrophic failure in Ref. 1)

2nd Defect

I noticed last fall that the floor level of the addition was several inches different from the floor of the older part of the building.  Such a difference in floor level contravenes some guidelines and could be construed as unsafe.  This is the second defect in this building of which I’m aware.

Cause of 2nd defect

The cause of the mismatched floors is certain to have occurred during planning and design of the room height in the addition – an initial hypothesis.  The floor to ceiling height in the existing building was not measured so planning and design could ensure the floor of the addition matched the floor of the existing.  Or it was measured but the information not used.

The difference in floor level would not be due to foundation settlement nor to building shrinkage.  The difference of several inches is just too great.

Two defects in the planning, design and construction of an addition to a building?  Overseered by planners, architects and engineers?  I’m certain someone was embarrassed back then.

No excuse for defects

Two defects in a building – one in the planning and design stage and a second in the construction stage – that should not have occurred.  These potential problems are too well known to experienced planners, architects, engineers and builders and could have been avoided.


  1. (Fairly easy) Estimating the investigative cost of a catastrophic failure.  August 13, 2013



My first “forensic engineering” investigation.

The following is one in a series of cases I have investigated that illustrate the different types of failures and accidents that occur resulting in civil litigation, and the forensic engineering methods I used to investigate the cause.  I investigated this failure when I was studying civil engineering at UNB and hardly knew what a forensic investigation was.

The investigation is reported under the following headings with several sub-heads:

  • The case (a description of the failed structure – significant cracks in a building - the “legal”/technical issues, and my “client”
  • Forensic engineering investigation of the failure and the methods used
  • Cause (of the failure)
  • Post mortem (an interesting side story and a lesson learned)

The case

I carried out my first “forensic engineering” investigation during my 5th year studying civil engineering at UNB.  As a student I had little or no understanding of forensic engineering and wasn’t even qualified as a professional engineer.

Nevertheless, this was a significant and costly building failure but, fortunately, not a catastropic one. (see pictures of a catastrophic failure in Ref. 1 above)

We took some of our lectures in a room on the second floor of a two story brick-walled building on the campus.

One day a 1″ wide, vertical crack appeared in the front, left corner of a wall of the lecture room.  (I measured the caulked crack last fall during our reunion)  You could see daylight through the crack.  This would be significant damage to an existing building

“Legal”/Technical issue

To me as a student with an interest in geotechnical and foundation engineering, the cause of the crack was interesting.  I investigated and reported on the cause to meet the requirements of one of my courses.


My “client” was the professor who was giving the foundation engineering course at UNB.

“Forensic engineering” investigation

My ”forensic engineering” investigation involved the following:

  • Visually examine the exterior of the building
  • Determine construction of the building’s foundations
  • Also construction of the addition to the building
  • Research construction techniques

Visual examination

A visual examination of the exterior of the building found that an addition to the building was being constructed adjoining the existing building.  Construction involved a deep excavation adjacent the existing building.  The sides of the excavation were supported by steel beams and timber planks.

Construction of the building’s foundations

I learned that the existing building was supported on shallow spread footings founded in the natural soils.  Excavating near and well below natural foundation soils requires their lateral support to prevent undermining the soils.  The soils could cave into the excavation - collapse catastrophically - unless properly supported.

Construction of the addition to the engineering building

I learned during my visual examination that the pile and plank, excavation support system installed by the contractor was a soldier pile shoring system.  This system is intended to temporarily support the sides of the excavation and in this way the foundation soils beneath the existing building.

Soldier piles are steel beams installed vertically in the ground at regular intervals of several feet at the side of where an excavation is planned adjacent existing foundations.  The piles are set deeper than the planned depth of the excavation.  The piles are driven vertically in the ground, or installed in previously bored holes eliminating the ground vibration from pile driving.

As the ground is excavated on one side of the piles, wood planks are placed horizontally bridging between the piles to hold the earth back on the other side – to shore up the side of the excavation from caving in.  In this case, the earth at the back is adjacent the earth comprising the foundation soils of the existing building.  The planking or lagging “follows” the excavation down.  This is a soldier pile shoring system.

A soldier pile shoring system is a good support system if constructed properly and its limitations kept in mind.

Research construction technique

I researched the soldier pile shoring system and found that it “gives” or yields a little – deflects along it’s height - when mobilizing its strength to provide support to the soil it is retaining.  The retained soil behind the shoring system gives a little as well - moves sideways and away from the foundation soils to which it is providing lateral support.  This undermines the foundation soils a little causing the soils to settle and the building foundations to settle as well.

This deflection is due to the piles bending along their length.  The piles will also tilt a little if they are not driven or embedded deep enough during installation.

This lateral movement of the shoring system and settlement of the soils and foundations is normal.  It can be negligible – tiny millimetres or less – if the shoring system is properly designed and installed.  The movement can be significant -  centimetres, inches or more – causing damage to the foundations, if the support system is not well designed and installed.

Installing soldier piles by driving them in place causes the soils in the immediate area to vibrate.  Soil settles when it is vibrated.  Anything in the soil – like building foundations - settles as well.


I analysed the data that I had collected – construction of the shoring system and the results of my research - and concluded the cause of the failure and submitted my student engineering report.

In this case the soldier pile system deflected too much causing the foundation soils to yield or move sideways and settle in the process.  This caused the building walls to settle as well and the corners to crack and open up.  The soldier pile deflection was probably due to a combination of the following causes noted above:

  • Vibration of the soils during installation of the piles
  • Tilting of the soldier piles due to shallow embedment
  • Deflection along the length of the piles

Post mortem

I passed my year so I must have got it right.  I understand that some of the engineers who inspected the soldier pile system that failed may have been my professors who had formed a consulting engineering company to do this type of engineering design and inspection work.  Failures occur in spite of the best efforts of the best people.



Figuring out the cause of forensic messes is not easy and takes time

So much of what we do in forensic investigation doesn’t lend itself to clean and tidy text-book investigation and analysis.  It’s messy and difficult to wrestle to the ground as to cause.  It also takes time.

I thought this after I posted a blog two weeks ago on getting hard evidence from soft data; getting the speed of a vehicle in an accident from the images on mobile phones. (Ref. 1)  I blogged at that time on a lecture by Major Adam Cybanski, Ottawa, on a new forensic method for assessing the speed of vehicles in an accident. (Ref. 2)

If you could see some of Adam’s lecture photographs and video showing aircraft, cars and people flying through the air and crashing, you’re certain to wonder: How can you measure and analyse something like that?  Disturbing images.  Surely traumatizing for the forensic investigator to see on site.

There was one picture of an airliner – not the TransAsia flight 235 crash mentioned in the lecture but that one too - nearly vertical in the air, nose down and a few metres from hitting the ground.  An aircraft filled with passengers.

If you could see the condition of some cars after a traffic accident that Dr. Stuart Smith and others in CATAIR investigate, that includes doing crush measurements, you’re certain to wonder about this too. (Ref. 3)  I’ve helped Stu a couple of times do these measurements; not a pretty sight.

Less visually disturbing – unless you are the owner – seeing undulating floor surfaces in multistory buildings or bent steel beams in half-built bridges you might wonder: How can a forensic expert analyse odd failures like these?

I sometimes wonder too and I come from a civil engineering background specializing in geotechnical and foundation work – measuring and engineering the messy ground.  We get it done because we have our models and semi-empirical relationships developed over decades of field observation, research and engineering practice.

Models help us figure out the cause of messy failures and accidents but their development takes time and lots of thought and hypothesizing.  I’m not surprised it took Adam months to get his analysis time down to a few days from a few months. (Ref. 1) In fact, I’m surprised it came together so quickly for him.

These models and analytical procedures show up in textbooks but not right away, not until someone has figured out the mess from a lot of failures.  I had one client surprised that forensic engineers must sometimes research topics for which little is known or vary geographically.  He thought we knew everything – a nice image.


(CATAIR; the Canadian Association of Technical Accident Investigators and Reconstructionists)

(Model: A set of ideas and numbers, based on existing data, that describe the past, present or future state of something.  For example, how the economy might react to a change in interest rates or a type of failure or accident occurred in the built environment.  Models are updated with new data as required.  After Merriam-Webster dictionary, January, 2018)


  1. Getting hard evidence from soft data.  Posted January 10, 2018
  2. Cybanski, Major Adam R., Gyro Flight and Safety Analysis, Ottawa, 2017
  3. Smith, Dr. Stuart, C. R. Tyner and Associates, Dartmouth, Nova Scotia

Optimism and confidence may impress the client but not Mother Nature (Ref. 1) Or, “How lucky do you feel…?” (Ref. 2)

Damaged foundations can result in civil litigation

I was contacted recently by a good friend in the U.K., Len Threadgold.  Len wanted to know how geotechnical investigation services are procured here.  This kind of investigation determines the physical properties of the soils and rocks that support foundations.  Engineers use this data to design the foundations.

Such an investigation is needed at every site because the foundation soil and rock conditions vary from site to site and across a site.  I learned when I practised in the U.K. to “Expect the unexpected” when assessing foundation soil conditions.  A similar mantra goes into the field with every geotechnical engineer in Australia – “If in doubt go deeper” – to stronger soils.  I had that drilled into me down there too.

Len is chairman and chief engineer of Geotechnics Ltd., a geotechnical and environmental engineering firm with offices in several cities in the U.K.  He was recently awarded the John Mitchell gold medal by The Institution of Civil Engineers (ICE) for “Excellence in geotechnical practice”.  Len will give a talk in London at the ICE on January 24 on Re-thinking Site Investigation – Design, Practice and Procurement to commemorate the award.

How is all this relevant to forensic engineering investigation?  Because many, if not most foundation failures are due to inadequate investigation of the ground which supports all building and civil engineering construction.  Damaged foundations can result in civil litigation.

Why are the investigations inadequate?  There are different reasons including foundation soil investigation services that are too often procured on the basis of low price in Canada and the U.K.

The barest minimum investigation is (too) confidently recommended in the interest of keeping costs down.  This can lead to foundation failure and major cost overruns – there’s no money in the quote for chasing the evidence across a site if unexpected conditions are found.  Cost and bottom line trump quality.

Often enough no investigation is carried out and hope rather than engineering analysis prevails.

Some studies in the U.K. indicated that project cost overruns due to unexpected ground conditions amounted to about 17.5% of project cost for highways (Ref. 3) while the cost of geotechnical investigation was on average 0.21% of project cost.  Cost overruns were 83.3 times as much as investigation costs!  If the difference between quoted prices for site investigation was 10% then this ratio becomes 833!! (Ref. 4) – not a sensible cost-benefit ratio.

So decisions on who to retain for a geotechnical investigation are based on trivial amounts of money, amounts much less than the cost of the reception desk in some offices and probably the cost of the opening ceremony. (Ref. 4)

I can’t help but think a similar situation exists here in Canada.

(Nor can I resist noting that some people shop around for expert forensic services on the basis of low price, and similar problems with inadequate forensic investigation may well result)

Parents instill confidence in us but remember Mom is just below the ground surface ready to scold if we accept low quality to save a dollar.


  1. After, Professor, Sir A. W. Skempton, U.K., “Optimism and overconfidence may impress one’s clients but they have no influence on the great forces of nature”.  Address of the President. Proceedings of the 5th International Conference on Soil Mechanics and Foundation Engineering, 3, 1961, pp 39-42.
  2. Clint Eastwood in the “Dirty Harry” movies, 1971 to 1988
  3. Stuart Littlejohn, Inadequate Site Investigation, The Institution of Civil Engineers, U.K., 1991
  4. Personal communication with Len Threadgold, Geotechnics Ltd., U.K., 2017 (An initial chat with Len on his ICE award gave me the idea to blog on this topic of inadequate geotechnical investigation, foundation failure and civil litigation)





C’mon, ‘fess up if you haven’t worked with experts before

It’s good for the judicial process and the injured party if you let us know if you’ve worked with experts in the past.  We catch on soon enough.  Get it out in the open at the start.  It’s also good for managing the cost of civil litigation.

Simply say, “I haven’t needed an expert before but do on this case”.  We all got to learn so it’s okay.

We can help you understand what’s involved in forensic investigation, what we need to do to be Rule 55 compliant (Nova Scotia) and how to manage costs.  Help you understand the investigative process that we must adhere to – our profession’s guidelines – in the same way experts are expected to have some understanding of the judicial process.

I’ve been blogging to that end for 5.5 years – to help you understand – and it’s paying off if reader feedback is any indication.  Still, some of you are a hard sell and cases go south for want of understanding.

I chide you about this because it’s important to get it out on the table.  I can help bring you along in this new relationship as you would me in understanding the civil litigation process.

I thought to suggest this after reflecting on some embarrassing exchanges over the years – another just recently – and not just with younger counsel.  One senior partner in a firm didn’t know that expert’s reports are sent via email today.  You could hear his silence over the phone.  Another estimated the total cost of a forensic engineering investigation at less than the invoiced cost of preliminary work.  Still another didn’t know that experts invoice on completion of individual stages in a forensic investigation, not for several stages in advance.

Don’t wing it.  Get it out there if you are relatively new to this.  You will learn how to work with an expert and control the cost of your case better.



Simple iPhone video taping an accident revises initial thoughts on cause

I was retained to investigate the cause of an accident involving the plaintiff using one of his tools.  People have been killed using this type of tool, it’s that dangerous.  The plaintiff believed there was a defect in the tool.  Graphic photographs of his injuries would certainly lead you to believe that - an initial hypothesis.

I was asked to peer review a report by another engineer and to examine the tool for wear sufficient to cause the accident.

The other engineer reported test-using the tool but, as evident in his report, not during a re-enactment of the accident.  He found a few things wrong with the tool but nothing to suggest it was defective.

I was surprised that the engineer did not re-enact the accident considering his stated years of experience investigating accidents.

I reviewed the report, researched howhis  the tool operated and examined the exterior.

I video taped the plaintiff re-enacting the accident and recorded his explanation of how he was injured.  I had him do this three times just to be sure and video taped his demonstration from different angles.

Evidence from the video and the interview was quite revealing as to cause but questions arose when this evidence was considered in light of evidence from the graphic pictures of the plaintiff’s injuries.

I retained a tool repairman to dismantle the tool and visually examine the interior surfaces for wear and defects.  He found nothing.

At this point in my investigation:

  • The nature of the injuries depicted in the pictures suggested one cause
  • The re-enactment suggested a different cause
  • The tool operated properly according to the repairman, supporting the different cause

The tie-breaker – justifying modifying the initial hypothesis on cause - were comments by the plaintiff during his interview on how he was using the tool coupled with how the tool operated.  Turns out he was using the tool in the most dangerous way, but one of several ways it could be used.  Also turns out that the material he said he was using didn’t exist as he described, except as a special order.  A similar, readily available material suited to the job he was doing could explain the contradiction raised by the graphic pictures.

To summarize the tie-breaking bullets:

  • The plaintiff said that he was using the tool in the most dangerous way, supporting the different cause noted above
  • The material he probably was using could explain a contradiction in the graphic injury pictures, also supporting the different cause

Based on the evidence, I modified my initial hypothesis that a defect caused the accident to believing that the plaintiff caused the accident by his actions when using the tool in the most dangerous way.


A spoiler?  As noted above, the plaintiff reported using the tool in the most dangerous way.  But, on being retained, I was given the tool rigged to be used in one of the safest ways.  This might have spoiled my modified hypothesis, but didn’t - the tool had passed through at least four sets of hands by the time I got it.

My client decided against further forensic investigation.


Design, manufacture/construction and maintenance/repair are three main stages in development and use of an item in the built environment, like a tool.  My investigation covered maintenance/repair when assessing if the tool in this incident was defective.

Retaining experts in design and manufacture to examine the tool would be a stage in a forensic investigation like this.  However, taking this step would not be justified considering the strength of the modified hypothesis and the cost of experts in design and manufacture.

My investigation several years after the incident cost money.  It would have cost less, as would the civil litigation in general, if I could have interviewed the plaintiff several days after the incident, or after my client took the case, and video taped him re-enacting the accident.  I’m certain the evidence from such simple tasks would have cast the merit of the case and the worth of the file in a quite different light.

Case take-aways

My take-away from this case is to get my iPhone out of my back pocket and video tape a re-enactment of an accident ASAP and have the victim describe it.  It might be rough – iPhone forensic video - but this quick and dirty stuff can pay dividends in a forensic engineering investigation.

My client’s take-away? Possibly an old saw – retain an expert early preferably during the merit assessment stage or a few days afterwards and save money on civil litigation.





Sinkholes: A litigious matter?

Sinkholes, like the one that undermined the house in Falmouth, Nova Scotia last week, are a serious issue for subdivision and lot developers.  As reported in the newspapers, the risk of sinkholes forming in an area can be known from published maps. (Refs 1, 2)  And the cavities in the ground associated with sinkholes can be found – before construction.

Sinkholes start their life as roofed-over cavities at some depth in the limestone, gypsum and salt deposits beneath an area.  The cavities get bigger and the roof gets thinner as rock like this dissolves in the ground water.  In a sense, the cavities “migrate” to the ground surface and eventually break through as sinkholes.  The fairly precise size, location and depth of cavities can be determined beforehand.

The technology for locating cavities in rock is well developed and has been around a long time.  It’s called ground penetrating radar, GPR for short, and it’s well known to experienced geotechnical engineers.  I used GPR years ago to locate cavities beneath an airport runway on South Andros Island in the Bahamas.  The same technique is used for locating unmarked graves.

It sounds technical but all it involves is sending radio waves into the ground and analysing what is reflected back.  There’s nothing too exciting in the data that comes from uniform soil or intact rock.  But lots of excitement in the data from a cavity, a well-recognized anomaly to the GPR operator – and a potential sinkhole beneath a building. The remote sensing, non-intrusive technique is not unlike CAT scans and MRIs in medicine.

The type of potential sinkhole I was looking for at the airport is called a banana hole. So named because banana plants grow in the sinkholes once the cavities break through the surface.  A banana hole/sinkhole can be seen in the runway by an inbound pilot but not the roofed-over cavity just before it breaks through the surface.

Geo engineers investigate the adequacy of the foundation soil and rock conditions beneath a site where someone wants to build something – like a house, for example, or a bridge, dam, or airport runway.  The conditions would not be adequate if there was a cavity beneath the building site.

GPR would not normally be used on a building site in the Atlantic provinces, nor in Canada for that matter.  But it certainly should if deposits of limestone, gypsum and salt are noted when the engineer checks the published geology of the site – an important and standard task in a geo investigation.  These types of rock with their inherent risk are not so common but they do exist as noted in the news report on the Falmouth sinkhole.

If there’s a risk and the technology is available to quantify it, and it’s not used, then it seems to me it’s a potentially litigious matter.


  1. Falmouth: Sinkhole wrecks family’s house, pg. 1, The Chronicle Herald, Halifax, Tuesday, September 5, 2017
  2. Geological conditions: Sinkholes not unusual in N.S.: Scientists, pg. 1, The Chronicle Herald, Halifax, Wednesday, September 6, 2017