Your classic "moving the goalposts" legal defense.

Courtesy of a once-upon-a-time post by Josh Marshall over at TalkingPointsMemo:

"Your honour, my client couldn't possibly have committed this murder since he wasn't even there at the time. But even if he was there, he didn't do it. But if he did do it, it was self-defense. And besides, that son-of-a-bitch deserved it anyway."

Sound familiar?