The U.S. Supreme Court wrestled last week with the issue of cellphone searches and whether police should be required to get a warrant before searching them.

Of course they should.

When the Constitution’s proscription against unreasonable search and seizure was written, people didn’t have cellphones in which they might carry private data. It’s a different world, but the constitutional standards must continue to apply: Americans have a right to privacy and before government can violate that right, its agents need a warrant.

There is little reason not to demand a warrant. It would be a rare circumstance that police, suspecting a cellphone might hold evidence, would need its information so urgently that they couldn’t first obtain a warrant. And if a judge won’t provide one, then police lack probable cause and shouldn’t be snooping there, anyway.

It is in some ways remarkable that this is even an issue, but the digital age has presented a number of issues that ought to be, but aren’t, self-explanatory. (How is it, for example, that purposely infecting a computer with a virus isn’t destruction of property? How is it that monitoring of digital data – whether done by individuals or the National Security Agency – isn’t electronic peeping-tomism?) The fact is that the law hasn’t caught up to technology and, given the rate with which technology changes, it’s possible that it never will.

But this issue is now before the Supreme Court, and the justices seemed puzzled. For example, Justice Samuel A. Alito Jr. asked, “What is the reasonable expectation of privacy of a person in 2014 who has a cellphone … on his or her person?”

The answer is: The same expectation one might have had without a cellphone. What’s his is his and police shouldn’t be prowling through it without a warrant.

Chief Justice John G. Roberts Jr. wondered about apps such as Facebook, accessible through cellphones, in which many people surrender privacy for the benefits of communication. Is it ripe for rifling?

The answer is: Unless police have legal cause to look through a cellphone’s contents at all, the question shouldn’t even arise. Leave it alone.

There is a concern, too, about the ability for parties from far away to wipe clean a cellphone’s contents. If that’s a genuine concern, then police should turn the phone off or pull the battery out. Searching doesn’t have to be the first step.

It’s true that, with weaker protections, police might apprehend some criminals by routinely poking through the contents of cellphones, but the same would be true if police were allowed to wander through homes at will, opening drawers, searching through purses, looking in closets. We don’t allow that, and for good reason.

We have constitutionally given up the occasional benefits of a police state to avoid the disastrous problems of a police state.

What is allowed is for police to protect themselves and to inventory the property of people charged with crimes. That’s a far cry from looking through a cellphone for evidence they are not otherwise allowed to search for.

The court should draw a clear line here. As we lose more and more of our privacy, the justices need to make a ringing defense of the ability of Americans to live their lives without having their phones or other electronic data improperly searched.

This shouldn’t be that hard.