Search Warrants

The Fourth Amendment forbids the search or seizure of an individual’s private property without a warrant. In practice, this means that a police officer or other government agent cannot enter your home to search it and seize evidence unless he or she has the permission of a judge to do so. When a law enforcement official is investigating a crime, he or she must assemble enough evidence to convince a judge that the violation of a suspect’s privacy and property is “warranted.” The standard for demonstrating the need for a warrant is that the government must show that it has “probable cause.” Of this standard, the Supreme Court observed:

In dealing with probable cause, . . . as the very name implies, we deal with probabilities. These are not technical; they are the factual and practical considerations of everyday life on which reasonable and prudent men, not legal technicians, act. . . . Probable cause exists where "the facts and circumstances within [the arresting officers'] knowledge and of which they had reasonably trustworthy information [are] sufficient in themselves to warrant a man of reasonable caution in the belief that "an offense has been or is being committed" (see Draper v. United States (1959)).

While police officers may make arrests and seize evidence if there is “probable cause” to do so, the Court has consistently upheld the rights of the people to be secure in their possessions and in their homes. For example, it has ruled that in the vast majority of cases, warrants must be specific with regard to the place to be searched and the items (or kind of items) to be seized. Police officers cannot obtain warrants to “snoop” around someone’s home simply because they are suspicious of them.

As is true with every right guaranteed by the Constitution, the right to be secure in one’s person and possessions is not an absolute right. The Court has identified reasonable limitations on the Fourth Amendment’s guarantees where the interests of the community are deemed more pressing than those of the individual.

For example, in an extension of the “probable cause” rule, the Court has found that evidence obtained in connection with an otherwise lawful arrest may be used in a trial, even if the arresting officer does not have a warrant.