Search Warrants: Supreme Court Cases, Amendment & Law

Instructor: Kenneth Poortvliet

Kenneth has a JD, practiced law for over 10 years, and has taught criminal justice courses as a full-time instructor.

The Fourth Amendment protects people from unreasonable searches and seizures and lays out the requirements for a search warrant. In this lesson, we will learn how Supreme Court decisions over the years have impacted those protections.

Do You Have a Warrant?

Claude ducked into his house, out of breath. An hour later, police crashed though his front and back door and arrested him. They found cash and drugs in his closet and told him they had a video of him dealing drugs. But don't they need a warrant before they enter his home?

The Fourth Amendment protects people from unreasonable searches of their person and places and requires that a search be based on probable cause. It states that ''no Warrant shall issue but upon probable cause, supported by Oath or affirmation particularly describing the place to be searched, and the persons or things to be seized.'' What's not stated is when a warrant is required. Over the years, the Supreme Court has set out some rules governing when a warrant is needed and what probable cause means.

The Warrant

A search warrant is an order issued by a judge that allows police to enter a protected area and search for evidence of a crime. The officer requesting the warrant from a judge must demonstrate that they have probable cause, which means that the officer reasonably believes that the place to be searched contains evidence of a crime.

For example, Ed and three of his buddies gets pulled over for speeding. The officer has a hunch that they have been drinking or smoking pot, but a hunch is not enough to search. The officer needs some evidence to cause him to believe that there probably is alcohol or marijuana in the car. Or put another way, the officer needs probable cause.

When Does Probable Cause Exist?

How does a police officer know that there is probable cause to conduct a search? The courts have used the reasonable person standard, which asks the question: would a reasonable person in the same circumstances believe that a crime has probably been committed or that there is evidence of a crime?

In Illinois v. Gates (1983), the court redefined the standard for probable cause. Police were granted a warrant based on an anonymous tip, and the Supreme Court held that when determining whether probable cause exists, the officer can look at the totality of the circumstances to determine if a reasonable person, under similar circumstances, would believe that evidence of a crime probably exists.

So for Ed and his buddies, if a hunch isn't enough for the officer, what would be? Let's say that Ed has bloodshot eyes, is slurring his speech, and the officer can smell alcohol and pot and see a baggie and a beer bottle top sticking out from under the seat. A reasonable person would look at the totality of the circumstances and believe a crime has probably occurred. Okay, so now we have probable cause, but do we need a warrant?

When Is a Warrant Necessary?

The Fourth Amendment says that no warrant shall be issued without probable cause, but it doesn't say if a warrant is needed for every search. Over the years, the Supreme Court has held that although probable cause is required for a search, a warrant is not always necessary. It comes down to the issue of privacy.

In Katz v. Ohio (1967), the Court created a line in determining when a warrant is necessary based on levels of privacy. They ruled that a person has an expectation of privacy in a phone booth even though it was in public. This was because the booth could be closed to create privacy. Though the agents had probable cause, they didn't get a warrant before they wire-tapped the booth, which means the arrest in this case was illegal.

Over the years, the court has ruled in specific cases on whether the level of privacy expectation required a warrant. Some of them are:

  • In the home: Expectation of privacy is high and a warrant is needed.
  • At work: Privacy expectations not as high as in a home, but still high enough to require a warrant.
  • In a car: Some expectation of privacy, but when driving out in public, a warrant is generally not needed (remember, probable cause is still required).
  • Walking around in public: No expectation of privacy for anything unconcealed, but some expectation of privacy exists for pockets, purses, wallets and other concealed areas. So a warrant might be needed to search a purse or a wallet.
  • In prison: Prisoners have almost zero expectation of privacy and are subject to searches of their cell and person.

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