Diminished Capacity Defense Restored in Michigan Courts
Michigan residents facing criminal charges may now use diminished capacity as a defense following a key court ruling.
Updated on Oct. 6, 2026 in Eldercare
The Michigan Supreme Court has reestablished diminished capacity as a legal defense, overturning a 25-year precedent. This shift now impacts ongoing criminal cases across the state, including the trial of Margaret Kempainen.
Why it matters
This ruling fundamentally changes how defendants can address mental health and cognitive status during criminal trials. It provides a new pathway for legal arguments regarding a defendant's capacity at the time an alleged act occurred.
The Michigan Supreme Court ruling in People v. Madison this summer restored the diminished capacity defense. This decision ended the 25-year precedent established by People v. Carpenter in 2001.
The players
Margaret Kempainen
A defendant facing two counts of homicide currently awaiting trial in the 12th Circuit Court.
Jacob Kempainen
An individual who received a 15-year prison sentence for second-degree murder in March 2026.
Anthony Ruiz
The attorney representing Margaret Kempainen who plans to file a motion for a diminished capacity defense.
The details
Diminished capacity allows a defendant to argue that their mental state prevented them from forming the specific intent required for a particular crime. Attorney Anthony Ruiz plans to utilize this change to challenge the two homicide counts facing Margaret Kempainen. The defense will argue that the defendant's mental state at the time of the 2023 incident should be a critical factor in the court proceedings.
Timeline
Alvin Kempainen was killed in his Hancock Township home in 2023.
Jacob Kempainen pleaded guilty to second-degree murder in December 2025.
Jacob Kempainen was sentenced to 15 years in prison in March 2026.
The Michigan Supreme Court ruled in People v. Madison in the summer of 2026.
A motion for the diminished capacity defense is planned before Christmas 2026.
Health Landscape
This development marks a departure from the 2001 People v. Carpenter case which previously limited the scope of mental health defenses in state criminal proceedings. The current ruling aligns with broader efforts to integrate cognitive and psychiatric health data into the legal process.
The restoration of this defense impacts how clinical evaluations of cognitive impairment may be utilized in legal settings. Residents with concerns about how neurological or mental health status interacts with legal matters should consult with qualified legal or medical professionals.
The takeaway
The Michigan Supreme Court has restored diminished capacity as a valid legal defense by overturning a 25-year-old precedent. Families managing care for aging relatives or those with cognitive health conditions should consult with an attorney regarding how these changes apply to specific legal circumstances.
Further reading
Find more information on legal and health support services on the Michigan Eldercare page.
Source note: This article includes information reported by K-Bear 102.
