A federal district court judge in Northern California ruled May 23 that police need a search warrant to peruse the contents of cell phones seized from people being arrested. While police may typically search people at the time of arrest and at booking, the judge held that searching a cell phone requires a search warrant.

The case arose from a December 2004 medical marijuana dispensary raid by the San Francisco Police Department in which five people were arrested. Three of them--Edward Park, Brian Ly and David Lee -- were taken to a local police station, where SFPD Police Inspector David Martinovich admitted searching one man's phone and ordering another police inspector to search the other two men's phones.

"I believed that a search of the cellular telephones at the police station during the booking process was permissible as a booking search," Martinovich said in court documents. He admitted perusing the cell phone and writing down the contents of its address book.

The three men filed a motion to suppress the evidence, saying the warrantless cell phone search violated the Fourth Amendment. US District Judge Susan Illston agreed.

"This court finds... that for purposes of Fourth Amendment analysis, cellular phones should be considered 'possessions within an arrestee's immediate control' and not part of 'the person,'" wrote Illston in her opinion. "This is so because modern cellular phones have the capacity for storing immense amounts of private information."

Illston expressed concern at violations of people's right to privacy. "Unlike pagers or address books, modern cell phones record incoming and outgoing calls, and can also contain address books, calendars, voice and text messages, e-mail, video and pictures. Individuals can store highly personal information on their cell phones, and can record their most private thoughts and conversations on their cell phones through e-mail and text, voice and instant messages," she noted.

"Any contrary holding could have far-ranging consequences," Illston continued. "At the hearing, the government asserted that, although the officers here limited their searches to the phones' address books, the officers could have searched any information -- such as e-mails or messages -- stored in the cell phones."

The government failed to show any purpose other than furthering criminal investigations, Illston concluded. "The court finds that the government has not met its burden to show, by a preponderance of the evidence, that it is standard police practice to search the contents of a cellular phone as part of the booking process," she wrote. "Indeed, the government has not articulated any reason why it is necessary to search the contents of a cell phone in order to fulfill any of the legitimate governmental interests served by a booking search: namely, to deter theft of arrestees' property and false claims of theft by arrestees, and to identify contraband and other items."

As Illston noted in her opinion, there is no controlling opinion on these issues in either the 9th US Court of Appeals or the US Supreme Court. In one similar federal case, the presiding judge found for the government. These issues are likely to be further adjudicated in the federal appeals courts.