Kant did not appear to grapple with the fallibility of the judicial system in the way that we do now, and I neither intend to defend his views or put words into his mouth on that point (though I welcome someone more knowledgeable in his work than I to do otherwise and cite). My point is that there aren't easy answers to these questions, which is why I upvoted the OP comment, because it implies a mature understanding that fallibility is also a value judgment.

(Edited for grammar. I hate typing on a smartphone.)

I believe he was a pretty "eye for an eye" guy: "This is the right of retaliation (jus [lex] talionis); and, properly understood, it is the only principle which in regulating a public court (as opposed to individuals’ private judgement), can definitely assign both the quality and the quantity of a just penalty." (http://acad.depauw.edu/~jeremyanderson/old/120s05/120z_kant....)

But you have to realize, this is not to be read in isolation as a rehash of Hammurabi''s code. There is significant axiomatic and theoretical foundation that brings Kant to this conclusion, which has significant influence in modern ethics.