Constructive Knowledge, Probable Cause, and Administrative Decisionmaking

58 Pages Posted: 17 May 2010 Last revised: 1 Nov 2017

See all articles by Simon Stern

Simon Stern

University of Toronto - Faculty of Law


This article examines the emergence, over the last two decades, of a doctrine that bases probable cause on the unshared knowledge of different law enforcement agents working together on an investigation. Thus if an officer conducts a search or arrest without probable cause, the action may be validated by looking to the other officers' knowledge. So far the rule has been confused with the "collective knowledge" rule and has traveled under that name. The article argues that the new rule (here called the "constructive knowledge" rule) depends on constructive belief and may establish constructive, not actual, probable cause. While the rule might seem to be justifiable on the ground that the officers would have pooled their information in any case, research on cognitive bias suggests that an after-the-fact analysis of the officers' knowledge would likely exaggerate any inculpatory evidence while disregarding exculpatory evidence. Fourth Amendment law imposes few formal ex ante requirements on officers, but some de minimis formality is appropriate here, as we may see by looking to the role of collaborative decision-making in administrative law. The article argues that courts should make explicit the rule's "inevitable communication" premise, and should refuse to aggregate the unshared information. Failing that, courts should require the prosecution to show that the officers would have shared their knowledge before leaving the scene. The "constructive knowledge" problem reveals the difficulty of factoring the risk of error into the analysis of probable cause when the requisite quantum of cause remains fixed in all cases. That difficulty, in turn, suggests that the probable-cause calculus may be likened to the Mathews v. Eldridge formula for termination of governmental benefits. This analogy points up other difficulties with the notion of "transsubstantive" probable cause.

Keywords: Criminal Procedure, Fourth Amendment, Probable Cause, Collective Knowledge, Constructive Knowledge, Inevitable Discovery

JEL Classification: K14, K42

Suggested Citation

Stern, Simon, Constructive Knowledge, Probable Cause, and Administrative Decisionmaking. Notre Dame Law Review, Vol. 82, No. 3, p. 1085, 2007, Available at SSRN:

Simon Stern (Contact Author)

University of Toronto - Faculty of Law ( email )

78 Queen's Park
Toronto, Ontario M5S 2C5


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