I don't know what the legal definition is, but the popular usage definitely implies guilt. EG, when the President pardons a crony, everyone knows he's totally guilt of whatever he was convicted of and more.

Is there a word which means a government acknowledges their laws were wrong and the people prosecuted under them were guiltless victims? If not, we could really use one.

There's a lot of that going around, and it'd be nice if governments had a word they should do more of.