MOORHEAD, Minn. (AP) — A Minnesota District Court judge from Moorhead is suing the state over the mandatory retirement age for his position.

Full-time judges and Supreme Court justices in Minnesota must retire when they reach the age of 70. Judge Galen Vaa tells KFGO radio the mandate is unconstitutional.

Vaa is suing Gov. Mark Dayton and the executive director of the Minnesota State Retirement System, David Bergstrom. Vaa's lawsuit says the judicial retirement law "is not absolutely necessary for the accomplishment of any legitimate public purpose."

The 68-year-old Seventh District judge says he's prepared to take his case to the Supreme Court if necessary.