What are the requirements of a valid warrant?

From time to time, this blog has mentioned that police officers must have a warrant to perform many searches. In fact, a warrant is often required before an officer can legally search someone, their house or their car -- unless an exception applies. Additionally, a warrant is often required in order for a law enforcement official to make an arrest.

If a valid warrant is not obtained before a search or arrest occurs -- and no exception applies -- then the search is considered illegal. Evidence obtained in an illegal search cannot be used in court. Therefore, if a warrant was not valid prosecutors may have a harder time obtaining a conviction. People may wonder, then, what makes a warrant valid?

In order for a warrant to be valid a sworn law enforcement official must bring it before a neutral judge. The judge will determine if the requirements have been met and will decide whether or not to issue the warrant. A valid warrant will be a written order signed by this judge.

While this blog post cannot determine if a particular warrant is valid, generally there are two requirements for a valid warrant. One, the judge has to find that probable cause that a crime has occurred or is about to occur. To prove this, the law enforcement official must make sworn statements to the judge and present evidence. This evidence can including a variety of statements including those made out of court.

In addition to probable cause, a valid warrant must have particularly. This means that the police officer that is trying to obtain the warrant must have limited the scope of the warrant. To fulfil this, the warrant must provide details about the place or the person that is subject to the search. For a home, for example, the officer must provide the address -- including an apartment number -- which they want to search. For individuals, in general, the descriptions must be complete enough so that a person with average intelligence could determine who the warrant was referring to.

Source: Findlaw.com, "The Fourth Amendment Warrant Requirement," accessed on Nov. 30, 2014