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This Article addresses two issues surrounding probable cause and reasonable suspicion that test the line between subjective and objective standards in Fourth Amendment jurisprudence: the extent to which a particular police officer’s training and experience ought to be considered in measuring probable cause and reasonable suspicion, and the relevance of the officer’s subjective beliefs about the presence of a weapon in assessing the reasonable suspicion required to justify a frisk. Although both questions have split the lower courts and remain unresolved by the Supreme Court, the majority of courts treat them inconsistently, recognizing the importance of an officer’s training, experience, and even knowledge in making probable cause determinations but ignoring her actual beliefs about the absence of a weapon in evaluating the permissibility of a frisk. This Article maintains that there is a connection between the two concepts and rejects the prevailing view that the former is a permissible objective consideration and the latter an impermissible subjective inquiry. Rather, the Article equates the two scenarios, concluding that just as a particular police officer’s knowledge, training, and experience can help inform the probable cause analysis, so too the officer’s subjective belief that a suspect is unarmed should be considered in deciding whether she had the reasonable suspicion necessary to frisk.


Publication Information: 12 University of Pennsylvania Journal of Constitutional Law 751 (2010).

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