The other examples in the list you quoted made sense to me, but this first one caught my attention.
My (admittedly lay) understanding of "affirmative defense" was a defense which acknowledged that the defendant had indeed committed the act in question, but had a legal justification or at least an excuse for doing it.
Or, in the words of Cornell's
Law School ...
I was puzzled to see "alibi" as the first point on the bullet list, since it is a defense which asserts that not only did the defendant not do it, but they weren't anywhere around when it happened.
Referring to the link for your cite, I find a different definition for "affirmative defense".
This would explain the inclusion of "alibi", but seems to suggest that
any defense action which proactively contradicts an assertion by the prosecution is an "affirmative defense".
I'm not familiar with this usage. Perhaps you could help explain it further. Is this just an obscure legal application of the term? Would it be helpful to the current discussion to appreciate the distinction between this usage and the one which is most commonly understood?