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The overwhelming majority of the Supreme Court’s Fourth Amendment cases over the past fifty years have been resolved using a warrant presumption model, which determines the constitutionality of a search or seizure by asking whether law enforcement officials had probable cause and a warrant, or some exception to those requirements. But three decisions, beginning in 2001, mysteriously deviated from that approach and applied a reasonableness balancing model, upholding the searches in those cases after considering the totality of the circumstances and weighing the competing government interests against the defendant’s privacy interests. This balancing approach has justifiably been criticized as amorphous, subjective, and overly deferential to government.

No announcement or explanation accompanied the Justices’ departure from the warrant presumption model. In fact, the Court claimed that it was simply following its “general Fourth Amendment approach.” Some scholars likewise believe that the Court’s Fourth Amendment jurisprudence has reflected this balancing approach for decades. And other academics fear that the Court has now completely replaced the warrant presumption model with the reasonableness balancing model.

This Article maintains that both of those claims are overstated. First, in exploring the origins of the reasonableness balancing model, the Article concludes that, prior to 2001, balancing was largely limited to Fourth Amendment cases requiring the Court either to decide on the creation and scope of categorical exceptions to the warrant requirement or to rule on the constitutionality of administrative inspections. Although general language suggesting a wider role for the balancing test can be found in a few Supreme Court decisions, those opinions derived support for a balancing analysis exclusively from warrant presumption model cases, did not stray far from that model, or have been undermined by later decisions. As a result, neither the Justices nor others have been able to find much in the way of precedent supporting an ad hoc balancing approach.

Turning second to the legacy of the reasonableness balancing model, the Article analyzes both Supreme Court and lower court decisions postdating the trilogy of opinions. This review finds that the Supreme Court has continued to apply the warrant presumption model in almost every Fourth Amendment case other than the three outlier opinions. The record in the lower federal and state courts is more mixed, and some courts have arguably attempted to extend the reasonableness balancing model into a few limited contexts beyond those involved in the three Supreme Court decisions. In general, however, the lower courts have been reluctant to apply the reasonableness balancing model aggressively and expand it into new arenas – with one exception, foreign intelligence and national security searches. Moreover, a number of lower court opinions have refused to engage in a balancing analysis or, though applying the balancing approach, have decided that the relevant law enforcement interests were outweighed by the defendant’s privacy interests.

While the Article finds that the reasonableness balancing model has not dramatically altered the Fourth Amendment landscape – at least not yet – that conclusion does not address the shortcomings of the balancing test. Most of the lower court opinions declining to use a balancing approach or balancing in favor of defendants have generated disagreement, either within the court itself or with other courts, and therefore could just as easily have been decided the other way. And some of the cases in which defendants prevailed under the balancing model were, or could have been, resolved under the warrant presumption model as well. Given the vagueness and malleability of the reasonableness balancing model, and the absence of any principled standard suggesting when it applies, the Article advocates that courts continue adhering to the warrant presumption model and exclude evidence discovered during warrantless searches that do not fall within one of the categorical exceptions to the warrant requirement.