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

Comments are closed.