What is Probable Cause for a Search Warrant?

Instructor: Kenneth Poortvliet

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

Police must have probable cause before a judge will grant a search warrant. In this lesson, we will look at the legal standard of probable cause and what circumstances must exist before a lawful warrant can be issued.

Evidence of a Crime

Carly watched the man walking his dog as he came toward her. The dog stopped and started aggressively sniffing her shoulder bag. The man pulled the dog back and walked on. A few hours later, Carly was sitting on her couch reading a warrant while half a dozen police officers searched her home. They found some marijuana in her son's room and they arrested Carly for drug possession with intent to distribute. Does this seem right?

Probable Cause for an Arrest or Search

Probable cause is a legal standard that requires specific circumstances be present before police can arrest or search. Probable cause exists when an officer reasonably believes, under the circumstances, that a crime has been committed and the suspect did it, or that evidence of a crime exists in the place to be searched. This is based on the reasonable person standard, which asks what a reasonable person (or in this case an officer) would believe or do under the same set of circumstances. This includes the training and experience of the officer, and the circumstances surrounding the observation.

Probable Cause for a Search Warrant

A search warrant, which allows an officer to search the subject (person or place) of the warrant, is not required for every arrest and search. The constitutional requirements of a search warrant are based on the Fourth Amendment, which says that ''no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.''

Often, an informant or witness is used to provide facts for the warrant. Before a judge will consider the warrant, the reliability of the witness will be scrutinized. Below are some examples that judges find reliable:

  • A confidential police informant with a reliable track record who can provide firsthand knowledge of a crime.
  • An informant who implicates themselves, as well as the target of the warrant.
  • An informant's information that is verified by police.
  • A crime victim's firsthand account of the circumstances.

Limits of a Warrant

A warrant is limited to the person, place and/or items for which there exists probable cause. For example, if the warrant allows you to search John's Mustang, it doesn't include his Charger as the probable cause exists only for the Mustang. If the warrant lists prescription drugs as the item to be seized, then the search can include any area in the specified place that can reasonably hold prescription drugs. In a home, this might include drawers, cabinets, desks, and closets. However, if the item looked for is a crate of 100 illegal assault weapons, then only areas large enough to fit assault weapons can be searched.

How Do Police Get a Warrant?

Let's say that Officer Clint wants a warrant to search the backyard and the garage of a house for a meth lab. Clint fills out the affidavit in the warrant, which is a written statement that is confirmed by oath and used as evidence in a court of law. It says:

''Probable cause for the warrant is based on the observations of a reliable informant who informed the police that a meth lab exists at the location.''

What's wrong with that? The information might be reliable, but how can the judge determine that by reading it? It is too vague and requires that the judge just accept the officer's and the informant's word about the existence of the lab. A better way to write it is:

''There exist probable cause for the warrant as an informant Joe, who lives next door, has observed the subject producing the meth in a garage kitchen. He has also purchased meth from him, was in the garage on several occasions, and witnessed both production and sales of meth. Also, he regularly sees equipment and chemicals stored in the backyard, as well as discarded containers and broken equipment.''

Clint gave the informant's name and created reliability by explaining that he observed the items in the backyard as a neighbor, and witnessed the production and sales in the garage as a buyer. This creates reliability because the informant is risking a criminal charge by giving that information, and he has personally witnessed the events and items. This creates liability beyond the word of the officer or informant.

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