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Privacy concerns are at their highest when police officers seek to enter a person's home. This means that except in emergency (called "exigent" in criminal law) circumstances, police officers must obtain search or arrest warrants before entering suspects' dwellings. (To learn more about the plain view doctrine and other exceptions to the search warrant requirement, see Search Warrants: What They Are and When They're Necessary.)
Below are examples of emergencies that may justify a warrantless entry into a home.
Example: Police officers are in hot pursuit of an armed robbery suspect. If the suspect runs into a dwelling, the police can follow and arrest the suspect. (But had the suspect run a stop sign and fled into his garage, the police would likely need a warrant to enter the home because the suspected crime is minor and doesn't justify a warrantless entry.)
Example: A police officer walking by an apartment house hears loud screaming coming from one of the apartments. In order to prevent injuries, the officer can use force if necessary to enter the dwelling without having to obtain a warrant first.
In order to gather information to support an application for a search warrant, law enforcement officers are typically allowed to take aerial photographs or come close enough to overhear conversations. However, they probably cannot use sophisticated equipment to discover what is on your property or to eavesdrop on your conversations (unless, of course, they already have obtained a warrant or qualify for one of the warrant exceptions).
A search warrant is a kind of permission slip, signed by a judge, that allows the police to enter private property to look for particular items. It is addressed to the owner of the property, and it tells the owner that a judge has decided that it is reasonably likely that certain contraband or evidence of criminal activities will be found in specified locations on the property.
As a general rule, the police are supposed to apply for a warrant before conducting a search of private property; any search that is conducted without a warrant is presumed to be unreasonable. This means that the police officers will later have to justify the search—and why a warrant wasn't obtained first—if the defendant challenges it in court.
A judge will issue a search warrant if the police provide enough information to show that:
The police usually provide information that is (1) based either on the officers' own observations, or (2) based on the secondhand observations of an informant.
If providing secondhand information, the police generally must convince the judge that it is "reliable." Usually, this means that the information is corroborated by police observation. For example, a citizen's tip that someone regularly delivers drugs to a certain location would be corroborated if an officer observes the person's routine.
However, corroboration of secondhand information is not necessary in every case. Sometimes a judge will issue a warrant if the source of the information is known to the police and has provided trustworthy information in the past.
Once the police have a search warrant, they are entitled to enter the designated property to search for the items listed on the warrant. Legally, the search is supposed to be confined to the specific areas described in the warrant. For example, if the search warrant includes only the living room, the search should not extend into the kitchen, bathroom, or bedroom.
But there are exceptions to this limitation which are frequently used to justify broader searches. For example, the police may search beyond the terms of the warrant in order to:
For instance, although a warrant might be issued for the search of a house, the sound of a shotgun being loaded in the backyard would justify expanding the search to the yard in order to protect the officers; similarly, a search limited to the ground floor might legitimately expand to the upstairs if the police, searching for illegal drugs, hear toilets being flushed above. And the police can always seize evidence or illegal items if they are in plain view or are discovered while the officers are searching for the items listed in the warrant.
No. In many situations, police may legally conduct a search without first obtaining a warrant. Here are some of the main exceptions (to learn more about these exceptions, see Search Warrants: What They Are and When They're Necessary):
The person in charge of the premises can generally allow police to search your apartment. If you and your roommate share common areas (such as the kitchen and living room), your roommate can authorize a search of those areas. But your roommate cannot give permission to search your separate bedroom.
Similarly, your landlord cannot give permission to search your apartment. However, if the police can point to circumstances that would justify immediate entry—such as the sound of a ferocious fight—they may enter without permission from anyone.
Yes. The police are allowed to conduct a thorough search of an impounded car, including its trunk and any closed containers that they find inside. This is true even if your car was towed after you parked it illegally or if the police recover your car after it is stolen.
The police are required, however, to follow fair and standardized procedures when they search your car, and may not stop you and impound your car simply to perform a search.
A police investigation constitutes a search if it intrudes on a person's "legitimate expectation of privacy." Courts ask two questions to determine whether a person had a legitimate expectation of privacy in the place or things searched:
If the answer to either of the above questions is "no," then the investigation is not a "search." (To learn more about what constitutes a legitimate expectation of privacy, see Understanding Search-and-Seizure Law.)