A must-see episode on every account, featuring The Doctor being "awakened" many years hence on an alien world, forced to account for the version of his crew's reputation that has survived there.
Beyond clever, this is exactly the kind of episode that the series had every potential to produce. The Doctor was the artificial being whose existence received the most exploration in the franchise, eclipsing Data in fairly quick order, moving past and then circling around the exact nature of his existence while also capitalizing on nearly every possibility with such regularity that he seemed to be the main character whenever he was in the spotlight, not just in the episode, but the series in general.
Anyway, to get back to "Living Witness" specifically, a backup program of The Doctor's is discovered in the wreckage recovered by Delta Quadrant natives who remember the Voyager crew as tyrants, and have simulations to prove it. The Doctor is thus in the unique situation to set the record straight, but will he believed? Every now and again, the series liked to explore what people who had no experience with the Federation might actually think of a Starfleet crew forced to represent its best ideals without any real sense that anyone but them cared about those ideals.
Anyway, it doesn't matter what I say about it. Watch it. Essential viewing. Anyone who can watch this episode and still dismiss the series can't be taken seriously.
franchise * series * essential * character
Memory Alpha summary.