In New York, a valid search warrant signed by a judge can give law enforcement officers the right to search your home or place of business (among other places) for evidence of criminal conduct. Sometimes search warrants are obtained after long criminal investigations, and sometimes they are applied for quickly in emergency cases in which law enforcement fears that evidence will be destroyed. A judge can sign a search warrant where he believes, based upon sworn affirmations made to him by law enforcement and/or civilian informants, that there is probable cause to believe that the targeted location contains evidence of criminality.
Most commonly, search warrants obtained by officers from the NYPD are sought for firearms or narcotics (though the list of possible reasons for a search warrant is endless). With respect to narcotics-related search warrants, police officers will typically not apply for a warrant until they can affirm to a judge that some police officer or police informant has either seen or purchased narcotics inside the location, and done so recently. (When information about possible contraband in a location is not recent, it is considered “stale” and insufficient to justify a search warrant.)