> If the cops accuse me of shooting someone in SF, but I was in Berkeley at the time, I might be tempted to tell them that. But then, when they produce a fault

> If the cops accuse me of shooting someone in SF, but I was in Berkeley at the time, I might be tempted to tell them that. But then, when they produce a faulty eye-witness, who says they saw me in SF that evening, suddenly I need to discredit that witness in order to resolve my alibi. you have an equal need to disprove the claims of a witness regardless of whether you have an alibi additionally, regardless of whether there's a witness, all you need to do is prove you were in Berkeley to remove yourself as a suspect so the two things (alibi, witness) seem orthogonal