What do you think? How do you express “the degree of certainty with which the expert holds the opinion”?

How do you express “the degree of certainty with which the expert holds the opinion” as required by some civil procedure rules in Atlantic Canada? (Ref. 1)  For example, Rule 55 in Nova Scotia.  Do you know?

What did the draftees of rules like this have in mind?

How do you indicate if the degree of certainty is high or low, or somewhere in between?  How do you indicate that it’s just over 50% or close to 95% or somewhere in between?

Most definitions of “degree” in different dictionaries include words like “steps”, “stages”, “grade”, “classifications”.  These words suggest to me something that can be measured, or at least the attributes of different levels of classification identified.

What words should we use if we use words?  If we use numbers, how do we measure “degree” of certainty?

Would the court expect an engineer or some other applied scientific expert to quantify the degree of certainty?  Engineers like to measure things and to some extent, the courts, judges, juries, counsel, the public, know and expect this.  How do you measure the degree of certainty?

It’s been said, if you can measure something you can manage it. (Ref. 2)  How do you measure the degree of certainty and manage to achieve an acceptable certainty when forming your opinion?

If we could measure it we could manage it and ensure it’s over 50%, say, or close to 95%, and assure the court that our opinion is correct.

Could you quantify degree of certainty by reporting that you carried out a certain number of studies of equal validity and more than half of those lead to your opinion?  Would that be quantification?

Is it necessary to quantify the degree of certainty, as engineers would like to do?  Or is it sufficient in Atlantic Canada to express an opinion in an expert report as follows, as recommended by one organization in the U.S. (Ref. 3):

It is my opinion “based upon a reasonable degree of (engineering, medical, legal, accounting, jewelry appraisal, or other field) certainty that …”

When I first read this recommendation I e-mailed the first author, Steven Babitsky, a former personal injury trial attorney, and was told this means “more likely or more probable than not and is legally sufficient”. (Ref. 4)  Is he saying “beyond a reasonable doubt”?  If this gets us just over the line, 50+%, what about all the other classifications of certainty between 50+% and 95%?

Are these words as suggested in the U.S. sufficient for the requirements of civil procedure rules like Rule 55 in Nova Scotia?  Are they a sufficient statement of  “the degree of certainty” as required by our courts?

What do you think?  How do we express the degree of certainty to the court?

Do we use words to express the degree of certainty?  If so, what might those different words be to indicate different degrees, steps, stages, classifications, etc. of certainty?  Or do we measure and quantify, and, if so, how do we do this?


  1. Civil Procedure Rules, The courts of Nova Scotia, Contents of Expert’s Report, Rule 55.04 (2) (c)
  2. Osborne, Jack, Personal communication
  3. Babitsky, Steven, and Mangraviti, Jr., James J., Writing and Defending Your Expert Report: The Step-by-Step Guide with Models, SEAK, Inc., Falmouth, Mass., 2002
  4. Babitsky, Steven, personal e-mail communication, August 19, 2009


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