Credit for good deeds
If some punk off the streets breaks into a house and rips off some jewelry, maybe I’d be willing to find mitigation in the fact that he also volunteers at the local soup kitchen, is nice to children, has a little dog named Smookums and was abandoned by his father when he was six. Theft from the public by a public official, whatever his character, is of a graver offense than one person stealing from another person, and nothing should mitigate its gravity.
This distinction is used to oppose good-deeds-related mitigation of the sentence of a state senator whose crime fell in the public category. I agree with his position on said senator. But I would go farther and argue that a person's other good deeds should never count as mitigation for a sentence, even for personal crimes.
The key issue to me is whether the justice system is judging actions or character. I think it should be the former -- you're called in front of the judge because of a specific act you did, and so the punishment should be based on the nature of the act and the likely consequences (deterrence, incapacitation, rehabilitation, etc) of punishing it. I think many of the problems in our current justice system (and in our society more generally) arise because of a desire to judge people's character -- that is, to punish them for being "bad guys," treating the crime at issue as merely a test to diagnose their bad-guy-ness. (That's why, for example, the definition of impermissible entrapment by the police is so narrow, and why parole and probation systems so often seem to be designed to make the parolee/probationer fail -- if you're looking to find the bad guys, it makes sense to provoke them into doing something bad so that you can get them off the streets and punished before they have a chance to commit a real crime.) The most obvious rationale for good-deeds-mitigation is a character one (Burke even uses the word "character" in the quote above) -- the good deeds show that you're not really a bad guy, so you don't deserve the kind of punishment we'd give someone whose crime revealed them to be a bad guy.
But good-deeds-mitigation is still problematic if we put it in an acts-based framework. Let's say Burke's hypothetical punk did all that good stuff, but didn't rob anyone's house. The court wouldn't call him in, hear the evidence about his good deeds, then award him some sort of bonus above and beyond the basic civil rights accorded to his less-public-spirited compatriots. But yet Burke, and our current justice system, would give him a bonus if he were caught committing a crime. (By the same token, I don't think that bonuses one might in fact get for one's good deeds -- say, a "volunteer of the year" award from the soup kitchen -- should be mitigated by unrelated bad deeds. I think Burke's punk should get the volunteer award and the full robbery sentence, since they're distinct things and he did the qualifying deeds for each, rather than getting neither because they cancel out.)
Indeed, one could read a good-deeds-mitigation scheme as saying that you can build up credit through good deeds, then use that credit to buy laxity about violating the rules -- serve enough soup at the soup kitchen, and we'll let you rob someone's house. But if there's a good reason to ban robbery and impose a certain size sentence on it, that reason is still good even if robbers do other charity work. And such a setup reinforces the pernicious idea that virtue consists in self-denial and all the fun stuff in life is against the rules.