WASHINGTON - Warrantless smartphone searches worried Supreme Court justices Tuesday, with several challenging law enforcement intrusions on privacy.

In a high-tech case that goes well beyond its San Diego origins, liberal justices in particular seemed poised to limit what police may do with iPhones and similar devices taken during arrests.

"Most people now do carry their lives on cellphones, and that will only grow every single year as, you know, young people take over the world," Justice Elena Kagan noted.

At the same time, pointed questions from conservative justices and persistent probings by Justice Anthony Kennedy, frequently a swing vote, hinted at a difficult split decision ahead.

"Smartphones do present difficult problems," acknowledged Justice Samuel Alito, a conservative who often sides with law enforcement.

The California smartphone case heard Tuesday, along with a somewhat different case involving a Massachusetts cellphone, brought justices face to face with devices that are banned from the courtroom itself. Most everywhere else, the phones are omnipresent and ever more powerful as far as range, capacity and utility.

Myriad applications, or apps, provide virtual access to medical, financial and personal records. Global Positioning System data is routinely stored, providing electronic footprints to past locations. Justices on Tuesday repeatedly noted the power of the technology, hinting that it will color their decision.

"With digital cameras people take endless photos and it spans their entire life," Justice Sonia Sotomayor noted, adding that "a GPS can follow people in a way that prior following by police officers in cars didn't permit."

The California smartphone case started when a San Diego police officer pulled over David Leon Riley on Aug. 22, 2009. Police impounded Riley's Lexus because he had been driving with a suspended license, and in a subsequent search they found two guns.

A police officer checked Riley's unlocked Samsung Instinct phone, and found video clips of gang initiation fights, pictures of gang signs and clips of a red Oldsmobile allegedly used in an earlier gang shooting.

Convicted on charges that included attempted murder, Riley was sentenced to prison for 15 years to life.