Japan's police want to read the phones of the men who give the orders. On September 2, a National Police Agency panel proposed it: reach into a suspect's phone from a distance and read what is said inside the secret apps. The targets are the tokuryu, the loose crews that hire strangers online for a robbery and never meet them.

There would be rules. A judge has to give permission first, a specially trained officer does the work, and whatever falls outside that permission is deleted. The suspect is told afterwards, and the public safety commission is informed.

The rules matter, and so does the clock. Arrest one member tonight and the group can throw away every phone it owns by morning. New handsets, new prepaid SIMs, contracts signed by somebody else, and for an operation like this it is only an expense.

So the tool is half of it. The other half is the person who signs a phone contract and sells it on for a little easy money. He is not the man at the door at three in the morning, but the order came through his phone. Make that the heavier crime it is, and let people see what it costs to be on that list.

Privacy and safety are not two doors where you pick one. Put the brakes in, then use the technology. Being careful is a reason to move well, not a reason to let the damage grow while the other side speeds up.