What Evidence Is Needed for a Search Warrant?

When it comes to obtaining a search warrant, what evidence do law-enforcement agents need?

In general, search warrants are governed by the Fourth Amendment of the U.S. Constitution. That means there must be probable cause to issue the warrant, based on an affidavit that describes the persons or things to be searched and seized.

So what is probable cause and what goes in a search warrant affidavit?

Probable Cause for a Search Warrant

Probable cause means that law enforcement must have a legitimate and reasonable reason to search or seize someone's property or to make an arrest. An officer who's seeking a warrant must specify his reasons for believing that:

• A crime was committed at the place to be searched, and/or
• Evidence of the crime is located there.

However, police don't need to be 100 percent certain that a crime was actually committed at the place to be searched in order to have sufficient probable cause for a search warrant. Those uncertain issues can be brought up later at trial.

For example, if a reliable informant told police that a house was being used to manufacture and sell drugs, and officers notice lots of foot traffic at all hours, they may have enough probable cause to ask a judge for a warrant -- even if they aren't totally certain that drug deals are occurring in the home.

Search Warrant Affidavits

The circumstances giving rise to the probable cause must be stated in an affidavit before a judge will grant a search warrant.

An affidavit is a written statement of facts that is made under oath. The key here is that the law-enforcement officer is swearing to the court that his facts supporting probable cause are accurate to best of his knowledge. The person making the affidavit can be guilty of perjury if he knows the information he's giving is inaccurate, but proceeds anyway.

An affidavit can include:

• An officer's own observations of criminal or suspicious activity, and/or
• Information from a third-party informant who may or may not be identified by name. Because this can be considered hearsay, a judge will also consider the veracity (or truthfulness) of the informant along with the informant's basis of knowledge.

Based on the facts given in the affidavit, the judge will determine if there's enough probable cause to issue a search warrant.

Although search warrants are needed before searching a home in most cases, police may not need one if there are exigent circumstances that require them to search the property immediately. And as mentioned above, search warrants can also be challenged in court; if a warrant is found to be invalid, all evidence collected pursuant to the warrant can potentially be thrown out.

If you have questions about how a search warrant was issued in your particular case, you'll want to discuss it with an experienced criminal defense lawyer right away.

Related Resources:

• Valid Search Warrant? 3 Things to Look For (FindLaw's Blotter)
• When Can Police Search Your Home? (FindLaw's Blotter)
• Drug Dogs Can't Sniff Homes Without Warrant (FindLaw's Blotter)
• Ask a Question About Investigations, Arrests, and Trials in Our Community Forum (FindLaw Answers)