(Tim Sloan/AFP/Getty Images)

Most every justice on the bench at the Supreme Court showed concern today for the issue presented in two cases addressing whether police need a warrant to search a cell phone incident to arrest.

But the justices struggled for two hours to come up with a reasonable rule to address privacy concerns and what one government lawyer called an "arms race between the forensic capabilities of law enforcement labs and the abilities of cell phone manufacturers and criminals to devise technologies that will thwart them."

Orin Kerr, a professor at the George Washington University Law School wrote in The Washington Post after arguments that "The rule that seemed to have the most support, at least based on the arguments, was some kind of middle ground rule. Several Justices seemed to want a rule that preserved some kind of search power in some cases but wouldn't let the government search everything in every case."

In general terms, courts have not required a warrant on a search-incident-to-arrest in order to protect evidence and officer safety. But today, Jeffrey L. Fisher, of Stanford Law School, argued that there are "very, very profound" problems with searching a smartphone without a warrant.

Fisher was in court defending his client David Leon Riley, a man pulled over for driving a car with expired tags. When cops found concealed and loaded weapons in the car they arrested Riley and seized his smartphone. One thing led to another and a warrantless search of the phone revealed photos and videos linking Riley to a recent gang shooting. Eventually, Riley received an extended sentence because of the gang affiliation.

Edward C. Dumont, Solicitor General for California, argued that the lower court had gotten it right that there was no need for a warrant to search the cell phone and he suggested there might not be huge privacy distinctions between pictures in someone's pocket and pictures seized from a cell phone.

Justice Elena Kagan pounced on that issue. She said to Dumont that under his theory, a person can be arrested for driving without a seat belt, "and the police could take that phone and could look at every single e-mail that person has written, including work e-mails, including e-mails to family members, very intimate communications, could look at all that person's bank records, could look at all that person's medical data, could look at that person's calendar, could look at that person's GPS and find out every place that person had been recently because that person was arrested for driving without a seat belt."

Kagan paused and said, "Now, that strikes me as a very different kind of world than the kind of world that you were describing where somebody has pictures of their family in a bill fold."

Chief Justice John Roberts wondered about being able to differentiate between different apps on a phone that might have different privacy implications. "Could you have a rule that the police are entitled to search those apps that, in fact, don't have an air of privacy about them?"

And he asked how a magistrate would be able to tell what part of the smartphone could be searched.

"If you're arresting somebody on the grounds of suspicion that he's a gang member and you have evidence to support that, what part of the smartphone is not likely to have pertinent evidence?" he said.

Justice Anthony Kennedy questioned if some distinction might be made between "serious and non-serious offenses."

Justice Ruth Bader Ginsburg suggested that if the police had seized the phone it could be preserved and officers would not be in any danger. "So I don't understand why we cut the warrant out of this picture," she said.

A second case before the court dealt with the implications of a much simpler Verizon LG flip phone. Brima Wurie, a Boston man was arrested in 2007 for distributing cocaine. After the arrest, police noticed that Wurie's phone kept receiving an external call from a number identified as "my house" on the caller ID screen. The officers opened the phone and accessed its call number. Through a reverse directory they were able to obtain an associated address which eventually led them to get a warrant and find a stash of crack cocaine.

Wurie was ultimately sentenced to 262 months in prison.

But he appealed his sentence arguing that the cell phone information should be suppressed. A federal appeals court ruled in his favor. The court worried about the treasure trove of information available on a phone.

Deputy Solicitor General Michael R. Dreeben argued the decision should be reversed. "The facts of this case," Dreeben said, "illustrate why any categorical rule that would preclude searches of cell phones incident to arrest would be inconsistent with historical practice and detrimental to law enforcement."

When Justice Kennedy asked Dreeben if he had any "limiting principles" to apply, Dreeben responded that the search "should be relevant to the crime of arrest" and said the court could articulate the rule in a way that would "prevent roving searches or speculative searches."

The justices acknowledged at times that the technology was difficult to keep up with.

Dreeben prefaced one question to Justice Steven Breyer by saying, "I don't know what kind of cell phone you have."

Breyer responded to laughter, "I don't know either because I can never get into it because of the password."

The court is scheduled to decide the cases by late June.