<P> Under the Fourth Amendment to the United States Constitution, most police searches require a search warrant based on probable cause, although there are exceptions . In the absence of valid consent or an exception to the warrant requirement, whether for purposes of effecting a search or an arrest, police entry in an individual's home always requires a warrant . The probable cause standard for obtaining a search warrant is lower than the quantum of proof required for a later conviction, proof beyond a reasonable doubt . </P> <P> Under the Fourth Amendment, search warrants must be reasonable and specific . This means that a search warrant must reasonably identify the items to be searched for and the place where law enforcement officials are authorized to search for those items . Unless an exception to the warrant requirement applies, the search of other buildings or areas of a building, persons or vehicles, or the search for additional items that do not reasonably fall under the original warrant, will normally require additional search warrants . </P> <P> To obtain a search warrant, an officer must prove to a magistrate or judge that probable cause exists for the proposed search, based upon direct information (i.e., the officer's personal observation) or other reliable information . An application for a search warrant will often rely upon hearsay information, such as information obtained from a confidential informant, as long as probable cause exists based on the totality of the circumstances . Police can seize both property and persons under a search warrant . The rationale is that evidence police collect without a search warrant may not be sufficient to convict, but may be sufficient to suggest that a warrant would allow police to find enough evidence to convict . </P> <P> The issue of federal warrants is determined under Title 18 of the United States Code . The law has been restated and extended under Rule 41 of the Federal Rules of Criminal Procedure . Federal search warrants may be prepared on Form AO 93, Search and Seizure Warrant . Although the laws are broadly similar, each state has its own laws and rules of procedure governing the issuance of warrants . </P>

Who has the power to issue a search warrant or a warrant of arrest