The Michigan Supreme Court hears arguments on the issue of guns in schools.
The case involves a man who openly carried a gun into a concert at a public school in Ann Arbor in 2015.
The court has been asked to consider whether public schools can ignore state law and adopt their own restrictions on firearms.
Michigan law does prevent people from possessing a gun inside a weapons-free school zone.
But there is a twist to the law.
Someone with a concealed weapon pistol permit can enter school property with a gun that is openly holstered.
This was the case in the Ann Arbor incident.
The school district was subsequently sued after banning all guns, even those covered in the state law.