Is there a case for a multi standard of care? No.

I thought there was a case for a multi standard of care, one that varied according to the stage of a forensic investigation.  But that’s not so.  However, there is a risk some people don’t understand this, or aren’t interested.

The standard of care in a nutshell is “…the degree of care a reasonable person should exercise”. (Refs 1, 2)

A reasonable engineer would do only what is appropriate to the stage of a forensic investigation which includes exercising common sense.  Others might do something different depending on their vested interests.

For example, a reasonable person might do a simple, approximate test of a material property in the early stage of an investigation, using readily available, inexpensive equipment .  Then later, if needed, after some results are in, a more accurate test with more expensive equipment.  The standard remains the same: – What a reasonable engineer would do at each stage.  What changes in this example is the test accuracy required and the test equipment used.

In general, this process is the scientific method.  It also reflects differential diagnosing in medicine.

It goes without saying that what is needed in an application of the standard of care is for the reasonable person to be suitably qualified and unbiased.


These thoughts were prompted by slip and fall accidents that I’ve investigated over the years, and the inevitable rebuttal of my reports on the accidents.

A fairly typical investigation of a slip and fall accident proceeds as follows:

I visit the scene three times.  The first visit to reconnoiter and visually examine the scene, walk around and “kick the tires” so to speak.  The second visit to have the victim re-enact the accident.  Also to simply slide the shoe the accident victim was wearing at the time across the floor and get some idea of how slippery it was.  The third visit to carry out manual drag sled tests to measure the skid resistance of the floor.  Drag sled testing is simple and inexpensive, exactly what a reasonable engineer would do at the start.

(You drag – pull – a known weight across the floor, measure the pull, divide the one by the other and get the skid resistance – the coefficient of friction like in high school physics)

In one case the victim was bare foot so I got a piece of pig’s belly, which is very similar to human skin, and pulled that across the floor – again, exactly what a reasonable engineer would do.  Pretty hard to drag a person’s bare foot across a floor.

When the tested skid resistance during a third visit is close to the lowest value possible for a material and well below that required for the floor and it’s foot traffic, I stop testing.  The skid resistant might be higher using a more precise and expensive test than drag sled testing but not at all high enough to classify the floor as safe.

How do I know?  The more expensive, precise test machine basically removes human error and bias from the testing.  The cheaper, less accurate drag sled testing removes a lot when we carry out a lot of tests.

The police do 10 tests with a drag sled when testing the skid resistance of a road at the scene of an accident.  I do 10 tests at each drag sled test location on a floor.  I also test several locations on a floor and test in different directions at each location, 10 times at each location and in each direction.

The rebuttal of my reports often reflects some knowledge of skid testing but the phraseology sometimes reflects bias in favour of the client too.  It’s also possible the writers have knowledge of the concept of the standard of care.  Unfortunately, the biased phraseology might call that knowledge into question.


There are several stages in all forensic investigation, from the simple to the complex.  Assessing cause also goes from the simple to the complex.  From a simple, initial walk over and visual examination of the exposed surfaces of a site to detailed intrusive examinations, measuring, testing – including full scale tests – and re-enactments of accidents.  For example, from estimating distance by pacing it off, to measuring distance with a tape, to using electronic measuring devices.

Forensic investigations stop at different stages too.  For example, after a simple walk over survey.  They can also stop after an investigator has done only simple testing.  Also after the extra cost of more accurate testing is not justified by the slight refinement in the test results.

Through it all the standard of care remains the same, “…the degree of care a reasonable forensic engineer should exercise”.  It doesn’t vary according to the stage of an investigation, the methods used or the cost.  No, not at all.  There’s only one standard, not many,


  1. Garner, Bryan A., Ed., Black’s Law Dictionary 4th edition 1996
  2. How the standard of care is determined when a failure or an accident occurs in the built environment Posted June 28, 2014.  Updated October 2017


  1. Nicastro, P.E. David E., ed., Failure Mechanisms in Building Construction, American Society of Civil Engineers (ASCE) 1997
  2. Black’s Law Dictionary, 4th pocket edition 2011
  3. Kardon, J. B. 2000, 2010 Chapter 7, Standard of Care in Forensic Structural Engineering Handbook, R. T. Ratay, Editor-in-Chief, McGraw-Hill, New York.
  4. Thompson, D. E. and Ashcraft, H. W. 2000, 2010 Chapter 9 Page 9.17 in Forensic Structural Engineering Handbook R. T.  Ratay, Editor-in-Chief, McGraw-Hill, New York.
  5. Association of Soil and Foundation Engineers (ASFE) 1985 Expert: A Guide to Forensic Engineering and Service as an Expert Witness
  6. Mangraviti, Jr., James J., Babitsky, Steven, and Donovan, Nadine Nasser, How to Write an Expert Witness Report, SEAK, Inc., Falmouth, MA 2014
  7. Kardon, Joshua B., Editor, 2012 Chapter 3, The Standard of Care in American Society of Civil Engineers, Reston, Virginia
  8. Tronto, J. C. (1993), Moral Boundaries: A Political Argument for an Ethic of Care, Routeledge, New York.
  9. Kardon, J. B. (2005), The Concept of “Care” in Engineering.  American Society of Civil Engineers, Journal of Performance of Constructed Facilities, Vol. 19, No. 3, pp. 256-260.

Posted by Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia, Canada, June, 27, 2019