The US supreme court needs to keep up with our cellphones -- and the NSA

[Commentary] The US Supreme Court arguments involved a seemingly basic legal question about the future of the Fourth Amendment: do police officers need a warrant to search the cellphone of a person they arrest?

But the two privacy cases pit against each other two very different conceptions of what it means to be a supreme court in the first place -- and what it means to do constitutional law in the 21st century.

"With computers, it's a new world," several justices reportedly said in the chamber. Are they ready to be the kinds of justices who make sense of it? Cellphones expose so much of our most personal data that the decision should be a 9-0 no-brainer.

The basic problem that makes it a harder call is that lawyers and judges are by training and habit incrementalists, while information and communications technology moves too fast for incrementalism to keep up. But this kind of narrow legalism simply cannot do when the world is changing as rapidly as it is today: all narrow analogies will systematically fail to preserve the values they did five or ten years ago, especially when we're walking around with all the metadata coming out of the bank/medical monitor/full-on GPS trackers in our pockets.

The world is changing, and that narrow view of constitutional adjudication will not offer us meaningful protection. What we need in these news cellphone cases is for those five justices to join together and show that constitutional vision is more than just the workmanlike competence of lawyers. Otherwise, the coming decades will become a series of lurches from one formally defensible but substantively implausible invasion to another, with no end in sight -- as long as there's another iPhone in the works.