I recently posted a revised draft of my forthcoming article, “The Effect of Legislation on Fourth Amendment Interpretation,” and I thought I would blog a bit about it. The article considers a recurring question in Fourth Amendment law: When courts are called on to interpret the Fourth Amendment, and there is privacy legislation on the books that relates to the government’s conduct, should the existence of legislation have any effect on how the Fourth Amendment is interpreted? And if it should have an effect, what effect should it have?

I was led to this question by reading a lot of cases in which the issue came up and was answered in very different ways by particularly prominent judges. When I assembled all the cases, I found that judges had articulated three different answers. None of the judges seemed aware that the question had come up in other cases and had been answered differently there. Each of the three answers seemed plausible, and each tapped into important traditions in constitutional interpretation. So you have a pretty interesting situation: Really smart judges were running into the same question and answering it in very different ways, each rooted in substantial traditions, with no one approach predominating and no conversation about which approach was best. It seemed like a fun issue to explore in an article.

In this post I’ll summarize the three approaches courts have taken. I call the approaches influence, displacement and independence. For each approach, I’ll give one illustrative case. But there’s a lot more where that came from: For more details on the three approaches and the cases supporting them, please read the draft article.

1. Influence. In the influence cases, legislation is considered a possible standard for judicial adoption under the Fourth Amendment. The influence cases rest on a pragmatic judgment: If courts must make difficult judgment calls about how to balance privacy and security, and legislatures have done so already in enacting legislation, courts can draw lessons from the thoughtful judgment of a co-equal branch. Investigative legislation provides an important standard for courts to consider in interpreting the Fourth Amendment. It’s not binding on courts, but it’s a relevant consideration.

The Supreme Court’s decision in United States v. Watson is an example of the influence approach. Watson considered whether it is constitutionally reasonable for a postal inspector to make a public arrest for a felony offense based on probable cause but without a warrant. A federal statute expressly authorized such warrantless arrests. The court ruled that the arrests were constitutional without a warrant and that the statute was constitutional. Justice White’s majority opinion relied heavily on deference to Congress’s legislative judgment. According to Justice White, the statute authorizing the arrests “represents a judgment by Congress that it is not unreasonable under the Fourth Amendment for postal inspectors to arrest without a warrant provided they have probable cause to do so.” That judgment was entitled to presumptive deference as the considered judgment of a co-equal branch. “Because there is a strong presumption of constitutionality due to an Act of Congress,” the court stated, “especially when it turns on what is ‘reasonable,’” then “obviously the Court should be reluctant to decide that a search thus authorized by Congress was unreasonable and that the Act was therefore unconstitutional.”

2. Displacement. In the displacement cases, the existence of legislation counsels against Fourth Amendment protection that might interrupt the statutory scheme. Because legislatures can often do a better job at balancing privacy and security in new technologies as compared to courts, courts should reject Fourth Amendment protection as long as legislatures are protecting privacy adequately to avoid interfering with the careful work of the legislative branch. The existence of investigative legislation effectively preempts the field and displaces Fourth Amendment protection that may otherwise exist.

Justice Alito’s concurrence in Riley v. California is an example of the displacement approach. Riley held that the government must obtain a search warrant before searching a cellphone incident to a suspect’s lawful arrest. Justice Alito concurred, agreeing with the majority only in the absence of adequate legislation regulating cellphone searches. “I would reconsider the question presented here,” he wrote, “if either Congress or state legislatures, after assessing the legitimate needs of law enforcement and the privacy interests of cell phone owners, enact legislation that draws reasonable distinctions based on categories of information or perhaps other variables.”

The enactment of investigative legislation should discourage judicial intervention, Justice Alito reasoned, because “[l]egislatures, elected by the people, are in a better position than we are to assess and respond to the changes that have already occurred and those that almost certainly will take place in the future.” Although Fourth Amendment protection was necessary in the absence of legislation, the enactment of legislation might be reason to withdraw Fourth Amendment protection to avoid the “very unfortunate” result of “federal courts using the blunt instrument of the Fourth Amendment” to try to protect privacy in emerging technologies.

3. Independence. In the independence cases, courts treat legislation as irrelevant to the Fourth Amendment. Legislatures are free to supplement privacy protections by enacting statutes, of course. But from the independence perspective, legislation sheds no light on what the Fourth Amendment requires. Courts must independently interpret the Fourth Amendment, and what legislatures have done has no relevance.

An example of independence is Virginia v. Moore, where the Supreme Court decided whether the “search incident to a lawful arrest” exception incorporates the state law of arrest. Moore was arrested despite a state law saying his crime could not lead to arrest; the question was whether the state law violation rendered the arrest unconstitutional. According to the court, whether state law made the arrest lawful was irrelevant to the Fourth Amendment. It was the court’s duty to interpret the Fourth Amendment, and what the legislature decided about when arrests could be made was a separate question. History suggested that the Fourth Amendment did not incorporate statutes. And the state’s decision of when to make arrests was not based on the Fourth Amendment and was based on other considerations, such as the costs of arrests and whether the legislature valued privacy more than the Fourth Amendment required. Constitutionalizing the state standard would only frustrate the state’s efforts to achieve those goals, as it would mean “los[ing] control” of the regulatory scheme and might lead the state to “abandon restrictions on arrest altogether.” For that reason, the statute regulating the police was independent of the Fourth Amendment standard.

Those are the three approaches. The next question is, which is best? I’ll offer some thoughts on that in my next post.