Suppose you were arrested—heaven forbid—for picketing an abortion center or absentmindedly bringing a pocketknife into a courtroom. If a police officer, after patting you down, began browsing private texts and photos on your cellphone, would you feel violated? In some states police have every right to do so, even without a warrant.

U.S. privacy laws are still catching up to the digital age. The Fourth Amendment protects Americans from “unreasonable searches and seizures” of their “persons, houses, papers, and effects,” but judges have ruled police may take wallets, weapons, papers, cigarettes, and other items found on a person’s body during an arrest. Usually, the amount of information gleaned from such items is quite limited.

A smartphone, on the other hand, can contain massive amounts of personal information not related to the arrest, such as family photos, work documents, and years’ worth of email correspondence.

Last fall a Michigan drug case demonstrated the ability of law enforcement to obtain info from mobile phones using digital extraction tools. After obtaining a warrant to seize and search the iPhone of a suspected drug dealer, immigration officials extracted call records, voicemails, photos, hundreds of text messages, a video, eight passwords, address book contacts, and other data indicating where the suspect had traveled.

Although a warrant was involved in that case, they aren’t always required. In 2011 the Supreme Court of California ruled 5-2 that police could search a cellphone discovered on a person during an arrest. (Oddly, if the phone was stowed elsewhere, such as in a piece of luggage, searching it would then require a warrant. A lock screen could also stymie police since they can’t force an arrestee to give up the password.)

Courts across the United States are inconsistent, though: Ohio’s Supreme Court in 2009 ruled that police cannot routinely search a person’s phone when making an arrest. A Rhode Island court held that text messages are potentially “intimate” and therefore protected, while a Washington court said texts shouldn’t be considered private. The U.S. Supreme Court has yet to weigh in.

In many cases police need only a subpoena—a court-approved document requiring less evidence than a warrant—to obtain a wealth of mobile information: phone call logs, geographic location data, or texts more than 180 days old. Law enforcement agencies are putting the info to energetic use: Mobile service providers fielded 1.3 million requests for data in 2011 from local and federal officials—thousands each day.

Evidence map

As Syria enters the third year of a brutal civil war, a project called “Women Under Siege” is using crowd-mapping technology to track incidents of sexual violence against hundreds of men and women. Crowd-mapping allows Syrian civilians to file online reports of rape and sexual attacks, compiled in a map at womenundersiegesyria.crowdmap.com. Allegedly, government forces have perpetrated most attacks, including gang rapes, though they remain unverified since Syria has barred foreign journalists.

The Women’s Media Center, whose co-founders include Gloria Steinem and Jane Fonda, runs the project. The documentation of assaults by Women Under Siege may provide evidence in future war crimes trials. —D.J.D.