This is covered in the article: Another problem is that CLEAR phones must resist "jailbreaking", i.e., must not let phone owners modify the operating system or

This is covered in the article: Another problem is that CLEAR phones must resist "jailbreaking", i.e., must not let phone owners modify the operating system or firmware on their own phones. This is because CLEAR critically relies on users not being able to tamper with their phones' unlocking functionality, and this functionality would surely be implemented in software, as part of the operating system or firmware, due to its sheer complexity (e.g., it includes the "device unlock request" screen, QR code recognition, crytographic verification of unlock codes, and transmission of data dumps). In practice, it is well-nigh impossible to prevent jailbreaking in complex consumer devices, and even for state-of-the-art locked-down platforms such as Apple's iOS, jailbreak methods are typically discovered and widely circulated soon after every operating system update.