Michigan Compiled Laws, Chapters 760 to 777 Code of Criminal Procedure § 768.13

Sec. 13.(1) A person who is being tried alone for an offense punishable by death or imprisonment for life, shall be allowed to challenge peremptorily 12 of the persons drawn to serve as jurors. In a case punishable by death or imprisonment for life that involves 2 or more defendants, a defendant shall be allowed the following number of peremptory challenges:

(2) In a case punishable by death or imprisonment for life, the prosecuting officers on behalf of the people shall be allowed to challenge peremptorily 12 jurors if a defendant is being tried alone or, if defendants are tried jointly, shall be allowed the total number of peremptory challenges to which all the defendants are entitled.

(3) On motion and a showing of good cause, the court may grant 1 or more of the parties an increased number of peremptory challenges. The number of additional peremptory challenges the court grants may cause the various parties to have unequal numbers of peremptory challenges.