What does "affirmative defense" mean?

An affirmative defense is a legal strategy where the defendant acknowledges that they committed the act but asserts that there are justifiable reasons for their actions that should exempt them from liability. This could involve presenting evidence or circumstances that provide a valid reason, such as self-defense or insanity. The key aspect of an affirmative defense is that it shifts the burden to the prosecution to disprove the defense's claims, rather than simply arguing that the prosecution has failed to prove its case.

In contrast, the other choices do not accurately encapsulate the concept of an affirmative defense. Claiming that all evidence is irrelevant does not address the act in question or provide a justification for it. Stating that the defendant was not present at the crime scene pertains more to a denial of involvement rather than an acknowledgment of an act with a justification. Lastly, using a tactic to delay court proceedings does not pertain to the merits of the case or present a legal reason for liability to be waived.