Search and Seizure

In any free society, the police must be constrained. The constraint can come from a variety of sources—politics, bureaucratic culture, administrative sanctions, and so forth. It need not necessarily come from the law. And in most Western democracies, it does not come from the law; outside the United States, police seem to be regulated, where they are regulated, mostly through nonlegal means.

For much of its history—until 1961, to be precise—the same held true of the United States. Since that date, however, American law has played a very large role in regulating the police and reining in police misconduct. And the chief source of legal restraint is the law of search and seizure.

That law has three key features. First, it is constitutional. The basic standards that limit police investigation of crime—the standards that define when police can search a home, or seize a suitcase believed to contain drugs, or arrest a suspect for some crime—derive from the Fourth Amendment to the federal constitution. Because judges are the prime interpreters of the constitution, this means search and seizure law is basically judge-made. Because constitutional law is binding on popularly elected legislatures and executives, it means search and seizure law cannot be altered by elected politicians, state or federal. In the United States, to a degree that probably has no parallel elsewhere, judges—especially Supreme Court Justices—decide what rules the police must follow. Congress, state legislatures, and the police themselves must live with the rules these judges and Justices create.

Second, its chief business is protecting privacy. The dominant focus of the law of search and seizure is to limit what police can see and hear, to limit their ability to invade spaces people prefer to keep private. That is not the only interest the law protects, but it clearly is the interest that the law protects most. Other concerns—the potential for police violence, the harm to individual liberty that comes from arrest or street detention, discriminatory treatment of black and white suspects—receive much less attention from judges and Justices in Fourth Amendment cases.

Third, it is police-focused. Government gathers information about people in a variety of ways, through a variety of agents. Grand juries subpoena witnesses and documents; prosecutors interview suspects; administrative agencies inspect wetlands and workplaces. These things receive only slight legal regulation; with few exceptions Fourth Amendment law ignores them. That law's clear focus is on police searches and arrests. It is not too much to say that Fourth Amendment law is a kind of tort law for the police; it is the body of civil liability rules that limit day-to-day police activities. Police must therefore pay close attention to Fourth Amendment rules; other government officials can usually ignore them.