key Assumption Check

Generally reconstruction of the past rests upon an a array of key assumptions that are received as true without any direct evidence. This is the primary reason a “Key Assumption Check” is a critical reoccurring analysis methodology in criminal defense investigations. For example, a leading premise in a criminal case may be the defendant is alleged to have traveled between to locations during the course of a crime. The assumption is just made based on direct evidence at both locations of the defendant’s presence at the location during some unknown point in time. However, no direct evidence shows the defendant traveling between the two different locations. Thus, this premise is a key assumption of the criminal analytical line or theory used by the prosecution.

Assumptions are made based on a past beliefs. Generally, these past beliefs are rooted in information that is routinely not questioned. The above example is an example of not questioning information. The objective of a Key Assumption Check is to ensure that an analytical judgments is not based on a flawed premise.[1] Secondly, this methodology allows a baseline of confidence to be established.[2] In turn, in the context of criminal defense, weaknesses in evidence can be uncovered and further exposed through investigation.

A Key Assumption Check allows a criminal defense investigation to meet the following objectives:

1. Separation of known and unknown information
2. Establish a baseline confidence
3. Focuses investigative efforts on weak assumptions or presumed evidence


The above description is written in the context of criminal defense investigations. The specific method is not limited to criminal defense, and can be applied to a wide array of problem sets.


1 Red Team Handbook. 5th ed. University of Foreign Military and Cultural Studies, 2011., p. 153
2 Pherson, Randolph. “The Tradecraft of Warning.” Pherson Associates, LLC (February 20, 2009): 1–8., p. 2
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