Your right to privacy when the police come knocking, pull you over, or stop you on the street.

What's Below:

When is a police investigation considered a search?
How private is your property?
What is a search warrant and what does it take to get one?
What are the police allowed to do after they obtain a search warrant?
Do the police always need a warrant to conduct a search?
Can my roommate -- or my landlord -- give the police permission to search my apartment?
If a police officer pulls me over, can she frisk me or search my car?
If my car is towed and impounded, can the police search it?

When is a police investigation considered 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:

• Did the person expect some degree of privacy?
• Is the person's expectation reasonable -- that is, one that society is willing to recognize?

If the answer to either of the above questions is "no," then the investigation is not a "search."

How private is your property?

Generally, a search takes place if the police have to enter your property in order to view contraband or evidence of a crime. The police can then use what they have seen on your property in order to get a search warrant. Or, if the situation calls for prompt action (the need to stop a drug deal in progress, for instance), they may enter your dwelling without a warrant.

How does this play out in real life? Law enforcement officers are allowed to take aerial photographs or come close enough to overhear your 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 get a warrant or qualify for one of the warrant exceptions).

The general rule is this: if the investigation method is highly artificial and high-tech, it's likely to be considered a search. Where the line is drawn, however, is not always clear and can vary from state to state. This will change if the U.S. Supreme Court decides whether the investigatory method constitutes a search for purposes of the Fourth Amendment; its decisions are binding on all states.

What is a search warrant and what does it take to get one?

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 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:

• it is more likely than not that a crime has taken place, and
• items connected to the crime are likely be found in a specified location on the property.

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.