That's a question the Obama administration wants the Supreme Court to answer in the affirmative.

Washington Post:

If the police arrest you, do they need a warrant to rifle through your cellphone? Courts have been split on the question. Last week the Obama administration asked the Supreme Court to resolve the issue and rule that the Fourth Amendment allows warrantless cellphone searches.

In 2007, the police arrested a Massachusetts man who appeared to be selling crack cocaine from his car. The cops seized his cellphone and noticed that it was receiving calls from "My House." They opened the phone to determine the number for "My House." That led them to the man's home, where the police found drugs, cash and guns.

The defendant was convicted, but on appeal he argued that accessing the information on his cellphone without a warrant violated his Fourth Amendment rights. Earlier this year, the First Circuit Court of Appeals accepted the man's argument, ruling that the police should have gotten a warrant before accessing any information on the man's phone.

The Obama Administration disagrees. In a petition filed earlier this month asking the Supreme Court to hear the case, the government argues that the First Circuit's ruling conflicts with the rulings of several other appeals courts, as well as with earlier Supreme Court cases. Those earlier cases have given the police broad discretion to search possessions on the person of an arrested suspect, including notebooks, calendars and pagers. The government contends that a cellphone is no different than any other object a suspect might be carrying.

But as the storage capacity of cellphones rises, that position could become harder to defend. Our smart phones increasingly contain everything about our digital lives: our e-mails, text messages, photographs, browser histories and more. It would be troubling if the police had the power to get all that information with no warrant merely by arresting a suspect.

I think most Americans understand the job of law enforcement and that in certain cases, granting them leeway in investigating criminal cases is necessary.

But while mulling the amount of privacy we're willing to give up, we should be mindful of the potential for abuse that exists in even the most well-intentioned law. This is the concern that undergirds critiques of the NSA programs and it should also play a role here.

Obviously, a ruling that agrees with the administration would be devastating to the concept of privacy. This mania to discover every tidbit of information about us has to stop somewhere. The Supreme Court would do well to stop it here.