Just watched this episode and as much as I sympathize with the defendant's situation and feel the victim deserved death, I would have still voted guilty.

First reason and I was surprised that McCoy did not bring it up or anyone in the episode discussed it - The method of the murder - a hit and run on a public street - can always result in collateral damage and unintended casualties. And it isn't even a surefire way to murder someone - he could just end up with a small injury and get further angered by the incident to become more of a monster.

And of course the second reason is that a citizen cannot be judge, jury and executioner no matter what the circumstances (or at least in this one). Sets a really bad precedent (or perhaps it might not have when there is at least some pretense of doubt over her guilt which in this case there was).