Backdooring isn't OK because by definition you cannot selectively backdoor someone's phone, you need to have it backdoored by default to exploit it later, which

Backdooring isn't OK because by definition you cannot selectively backdoor someone's phone, you need to have it backdoored by default to exploit it later, which is obviously terrible. Wiretaping a suspect's phone on the other hand is a fine (and often necessary) police operation, as long as it must be approved by an independent magistrate.