The upcoming version of Apple’s iOS mobile operating system has a feature that people are calling the “cop button,” as it would stop authorities from being able to unlock your iPhone or iPad by forcing you to place your finger on the Touch ID sensor.
As discovered by a programmer who was playing with the beta version of iOS 11—and reported by The Verge—if you rapidly press the power button five times, access via Touch ID is disabled, requiring you to enter your passphrase to unlock your phone or tablet.
Currently, disabling Touch ID means diving into the settings menu—after first unlocking the device, naturally. Alternatively, it means turning off the phone, turning it on again and making several unsuccessful attempts to log in with Touch ID. The five-rapid-presses method doesn’t just streamline that process; it also brings up the option of calling the emergency services.
So, is this really useful for protecting your phone from unwanted searches? The jury’s out on that one.
It’s certainly true that U.S. authorities have been able to compel people to unlock their phones with their fingerprints. This notably happened in Los Angeles in April 2016, when a court granted a search warrant forcing an alleged gang member’s girlfriend to unlock her phone in this way.
Get Data Sheet, Fortune’s technology newsletter.
However, authorities have also been allowed to demand that people give up their phone’s passcodes. Civil liberties activists say this should be banned under the Fifth Amendment, which says no-one should be compelled to be a witness against themselves, but in late 2016, a Florida court disagreed.
Border control authorities in the U.S. have even broader abilities to search through people’s stuff. They can’t force people to unlock their phones or laptops, but they can seize them and copy the data from them—a fact that makes it easy for them to coerce travellers into voluntarily unlocking their devices.
As phrased by The Grugq, a well-known (if pseudonymous) operational security expert with a prominent Twitter presence, Apple’s new feature may just be “a feel-good toy for people that will never experience risk if their security fails.”
Nonetheless, if it does make it into the final version of iOS 11—which is coming out in the Fall—the “cop button” could provide a potential point of friction between Apple and U.S. law enforcement. In early 2016, the Justice Department went to war with Apple over the locked phone of a dead terrorist, although it eventually dropped its case and accessed the phone with the aid of hackers.