Final answer:
The defense to first-degree murder that reduces the crime to third-degree murder is the 'Heat of Passion' defense.
Step-by-step explanation:
A defense to first-degree murder that reduces the crime to third-degree murder is the 'Heat of Passion' defense. This defense argues that the defendant acted in the heat of passion, which caused them to lose control and commit the crime. It is often used when the defendant can claim a provocation or sudden emotional reaction that led to the murder.
For example, if someone walks in on their spouse cheating, and in a fit of rage, they kill the other person, this could be argued as a 'Heat of Passion' defense. The defendant would need to prove that their actions were a result of the sudden emotional response and not premeditated.
It is important to note that the 'Heat of Passion' defense may vary in its application depending on the jurisdiction. Some jurisdictions may allow the reduction of first-degree murder to second-degree murder, while others may allow it to be reduced to third-degree murder.