Legal causation in bodily injury: Forensic engineer’s view

A plaintiff’s lawyer doesn’t have a reliable legal claim – and money well spent on a medical expert, until the technical issues in a personal injury case are identified and investigated, and the cause of the accident established.  Only then can the responsible parties be reliably identified by the lawyer.

I know this because I have been retained as an expert to investigate the cause of accidents like slip and fall, motor vehicle, toxic fume emission and ladder falls.  There are different elements in cases like these.  Legal and medical elements are two.  The technical element is another – an important one that comes first in a personal injury case if it’s to start off on the right foot.

There are also several different involved parties depending on the technical cause of the accident – at least four in a slip and fall accident. (Refs 1, 2)  And a similar number in a ladder accident.

I was reminded of this when I read about the plaintiff legal practice conference entitled “The Doctor Is In: Medical Elements of Injury Cases”.  It’s planned for this June in St. John’s by the Atlantic Provinces Trial Lawyers Association (APTLA).

The two day conference looks extremely good for practicing lawyers with at least a dozen featured topics and national and international speakers from the medical and legal professions. The topics are medical or closely related as would be expected.  The topics on the law of expert evidence and preparing to discover an expert are also timely, particularly to those of us retained as experts.

An important two-part topic is on causation:

  1. A pathologist’s view of medical causation in bodily injury
  2. Legal causation, the law and variance from medical causation

This topic really needs to be treated in three parts for an even more complete and comprehensive conference:

  1. A pathologist’s view of medical causation in bodily injury
  2. Legal causation, the law and variance from medical causation
  3. A forensic engineer’s view of technical causation in bodily injury and how it varies from legal causation

How can a lawyer confidently and reliably process a plaintiff’s claim for damages arising from bodily injury when he or she doesn’t know the technical cause of the accident and from that the party(s) responsible?  The emphasis is on confidently and reliably because lawyers are doing it now and managing often enough.  But that’s not good enough.

Establishing causation involves a two-stage inquiry: (Ref. 3)

  1. The first stage involves establishing ‘factual’ causation.  That is, determining exactly what happened and who might have been involved in the incident.  This is the forensic engineering investigation.
  2. The second stage involves establishing ‘legal’ causation.  This is when a lawyer reviews the factual causation – after it’s been established, and determines if the law is involved in the incident.

Determining factual causation in cases like the following is not lawyer-work.  It’s not even in the engineering text books in some cases and for certain not in the medical and legal text books.  A forensic engineer often has to “figure it out” as he goes along.

And often enough there is more than one party involved in what happened.  These parties are not known until the engineering investigation is complete.  I’ve seen the wrong party named in cases that were filed months, sometimes years before I was retained to investigate an incident.

Some examples of personal injury cases:

  • I used a piece of pork belly – a pig’s belly skin, to investigate one slip and fall accident,
  • also showered and walked across an accident site dripping water from my bathing suit to learn where water on a floor came from,
  • investigated soap detergent on a stair landing at a retail outlet,
  • carried out full scale field tests in a fatal motor vehicle accident,
  • planned full scale tests using a Hollywood-style stunt man in a fatal step ladder accident,
  • researched how a building “breaths” in one toxic fumes emission case and
  • how fuel oil weathers in the ground in another, and,
  • used binoculars to establish the cause of a man’s head injury from falling ice.
  • a colleague investigated a trip and fall accident where the injured party was half-running backwards

Cases like these don’t get resolved until the technical issues are identified and investigated.  One of the above cases went on for 11 years then settled in 4 months after I completed my engineering investigation and established cause.  Many months to a few years is normal.  For sure, some of the delay is due to short comings and backlog in the justice system but not all.

I’ve seen similar situations in cases involving structural deficiencies and engineering failures and collapse in the built and natural environments as distinct from personal injury accidents.

Until the technical issues are identified and investigated thoroughly, technical causation established and the involved parties identified, the doctor’s view of medical causation might suffer for lack of some technical data.

And the practicing plaintiff lawyer won’t know who to sue, confidently and reliably – he could well be out on a limb.  To borrow and modify a comment in the description of the conference topics, “Don’t let (missing data on technical) causation sink your case”.

A three-part topic on causation is needed at the conference in St. John’s in June – medical, legal and technical – if the APTLA membership and their plaintiffs are to be even better served.


  1. Sebald, Jens, Phd, System Oriented Concept for Testing and Assessment of the Slip Resistance of Safety, Protective and Occupational Footwear, Pro Business Gmbh, Berlin, 2009
  2. Di Pilla Steven, Slip, Trip, and Fall Prevention, a Practical Handbook, 2nd ed., CRC Press, New York, 2010
  3. Wikipedia, April 12, 2016




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