Before the age of smartphones, it was impossible for police to gather this much private information about a person’s communications, historical movements, and private life during an arrest. Our pockets and bags simply aren’t big enough to carry paper records revealing that much data. … The fact that we now carry this much private, sensitive information around with us means that the government is able to get this information, too.

The type of data stored on a smartphone can paint a near-complete picture of even the most private details of someone’s personal life. Call history, voicemails, text messages and photographs can provide a catalogue of how—and with whom—a person spends his or her time, exposing everything from intimate photographs to 2 AM text messages. Web browsing history may include Google searches for Alcoholics Anonymous or local gay bars. Apps can expose what you’re reading and listening to. Location information might uncover a visit to an abortion clinic, a political protest, or a psychiatrist.

(Hat tip: Timothy B. Lee)