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This paper comments on recent Supreme Court opinions that have used phrases such as "reasonable belief" and "reason to believe" when analyzing intrusions that generally require proof of probable cause. Historically, the Court used these terms as shorthand references for both probable cause and reasonable suspicion. While this lack of precision was unobjectionable when the concepts were interchangeable, that has not been true since Terry v. Ohio created a distinction between the two standards. When the Justices then resurrect these terms without situating them in the dichotomy between probable cause and reasonable suspicion, it is not clear whether they are adopting the reasonable suspicion standard (which the phrases more closely resemble), using the "reasonable belief" definition of probable cause, or creating a smokescreen, surreptitiously setting the stage for abandoning the two-tiered approach to probable cause/reasonable suspicion in favor of a sliding-scale model of probable cause.

In addition to confusing the concepts of probable cause and reasonable suspicion, the Court's use of terms like "reasonable belief" - whether careless or deliberate - leaves the door open for those who would draw a line between minimally and highly intrusive searches, whether based on a search warrant or some exception to the warrant requirement. By conflating probable cause and reasonable suspicion, the Court thus risks watering down the showing needed to obtain a warrant and thereby diluting the protections of the Fourth Amendment. Any such fundamental alterations of Fourth Amendment jurisprudence should be made transparently and not accomplished by means of indirection.