The Michigan Supreme Court tends to be somewhat hostile to common law, trying to find every which way to strictly rule by statute.
In People v. Reese No. 142913, released May 12, 2012, the Court ruled that the Imperfect Self Defense rule is not recognized in Michigan. The rule, whereby one who imperfectly uses force in self-defense can argue to receive a lesser conviction of manslaughter rather than murder when they do not fully follow the rules necessary for a self-defense claim, such as engaging in mutual combat or being an initial aggressor.
We hold that the doctrine of imperfect self-defense does not exist in Michigan law as a freestanding defense mitigating murder to voluntary manslaughter, although we recognize that factual circumstances that have been characterized as imperfect self-defense may negate the malice element of second-degree murder.
The court ruled that the murder laws were codified in Michigan prior to the creation of the common-law imperfect self-defense doctrine and as such, it is invalid and not recognizable as a rule because it was never codified.
Of course, this opinion is based on some pretty bad facts, beginning with the defendant's denial that he shot the dead person and then his claiming to act in self-defense for something he didn't do. It then got better from there. Not to mention the witnesses seem to indicate this was a case of mutual combat and not that the defendant was the victim of an attack by the deceased.
Not a lot of material for a winning argument, and in analyzing the facts presented this doesn't look like imperfect self defense at all. Instead it really does look more like conduct meriting a second degree murder conviction than manslaughter factually, and the self-defense claim seems a very far reach by the defendant.
Unfortunately, this lousy set of facts and argument opened the door for the Supreme Court to get rid of a doctrine they don't like, and such a doctrine that could have protected far more sympathetic defendants with better factual circumstances in the future.
Now instead of the imperfect self-defense rule mitigating bad circumstance self-defense to manslaughter, it will turn even more on the facts and circumstances to mitigate such a charge, making it harder for defendants in the future to take advantage of such a reduction.
To err may be human, but your self-defense claim, at least in Michigan, can't be imperfect.