Maryland residents likely know that the Fourth Amendment to the U.S. Constitution protects them from unreasonable searches and seizures. This is why police officers in the United States are usually required to obtain search warrants from judges or magistrates before searching suspects or their property. There are some narrow exceptions to the warrant requirement, but most police searches are conducted with judicial approval. Before this approval is granted, police officers must convince judges or magistrates that they have good reason to conduct searches.
Judges do not grant search warrants because police officers believe that evidence may be discovered. Instead, they require police officers to show that they have probable cause to search. Police officers establish probable cause when they have good reason to believe that evidence will be discovered at the location to be searched, but this information must be reliable. Information provided by a credible witness or a confidential informant would probably be considered reliable by a judge, but an anonymous tip would probably not be.
Obtaining a search warrant does not give the police officers involved permission to do whatever they like when they conduct their search. Judges take the Fourth Amendment very seriously, so they restrict the scope of the search warrants they issue based on the evidence presented to them. Search warrants may only give police officers the legal authority to search certain areas of a home or building or only look for certain types of evidence. These restrictions are included because the Fourth Amendment states that search warrants must describe the place to be searched and the evidence to be seized. Restricting the scope of search warrants also prevents what legal experts call “fishing expeditions.”
Challenging search warrants
The Fourth Amendment requires police officers to obtain warrants based on probable cause before they conduct searches, but obtaining a warrant does not always make a search legal. A court could rule a search illegal even if a search warrant was issued if the police officers involved misled the issuing judge or exceeded the scope of the warrant.