A more thorough explanation:

People v. William Freeman (1847) was a landmark case in the United States legal system. It was the first case where a defendant used an insanity defense. The case was heard and decided by the New York Supreme Court.

Background: William Freeman was a Black and Indigenous man who was convicted of stealing a horse and sentenced to five years of prison with hard labor. During his imprisonment, he would often refuse to work and proclaim his innocence instead. In response, he would be beaten by the prison guards. One of these beatings resulted in Freeman receiving a severe brain injury, which gave him mental confusion and deafness. Six months after he was released from Auburn Prison, Freeman was accused of murdering four members of the Van Nest family in Cayuga County.

The Trial: William H. Seward decided to take the case as Freeman’s lawyer, believing that Freeman had a mental illness and should not be held responsible for his actions. He argued that Freeman was insane, and brought in witnesses who testified about what Freeman was like before his injuries and after. He also brought in medical experts who testified that they believed Freeman was insane. Despite these efforts, the jury still found Freeman sane and competent for the trial, and the case was moved forward. During the trial, the judge refused to let in the medical expert testimony proclaiming Freeman as insane. After both sides presented their evidence, the jury found Freeman guilty of the murders and he was sentenced to death.

Appeal: Seward continued to advocate for Freeman after the trial ended and filed an appeal, arguing the trial court should have allowed the medical testimony to be presented to the jury. The appellate court reversed the trial court decision and held that even if a defendant is held to be competent enough to stand trial, they can still present evidence during the trial to support their defense of insanity. Freeman was granted a new trial but died soon after the appellate court decision.

Example: People v. William Freeman (1847) was a significant case in the United States legal system because it was the first case where a defendant used an insanity defense. William Freeman was accused of murdering four members of the Van Nest family in Cayuga County. His lawyer argued that Freeman was insane, but the jury still found him guilty. The case was later appealed, and the appellate court held that even if a defendant is held to be competent enough to stand trial, they can still present evidence during the trial to support their defense of insanity.