For the sake of national security, Apple must assist the FBI in breaking into a seized phone. This particular iPhone 5C, said to belong to San Bernardino shooter Syed Farook, was lawfully obtained by the FBI pursuant to a warrant to search Farook’s Lexus. It may lead the authorities to additional terrorists living in our midst—if law enforcement can obtain access to its contents.

The issue here is practical, not legal. Nobody denies, not even Apple, that the FBI may lawfully search the contents of Farook’s iPhone. The problem is that the phone’s software prevents the FBI from performing its search. The phone is encrypted and locked with a passcode that imposes three barriers to access.

First, the iPhone’s software includes an option to erase the phone if more than 10 unsuccessful passcode entries are made. There is no way to know if Farook enabled this software option. Second, the iPhone’s software requires that the passcode be entered by hand using the device’s touch screen. Third, the iPhone’s software imposes a waiting period between unsuccessful passcode entries. Without these hurdles, the FBI could use a brute force attack using a computer to enter possible passcodes until it finds the right one and unlocks the phone.