Mich. Comp. Laws § 768.29: Judge's duty at trial; effect of failure to instruct.

Sec. 29.

It shall be the duty of the judge to control all proceedings during the trial, and to limit the introduction of evidence and the argument of counsel to relevant and material matters, with a view to the expeditious and effective ascertainment of the truth regarding the matters involved. The court shall instruct the jury as to the law applicable to the case and in his charge make such comment on the evidence, the testimony and character of any witnesses, as in his opinion the interest of justice may require. The failure of the court to instruct on any point of law shall not be ground for setting aside the verdict of the jury unless such instruction is requested by the accused.