HELENA, Mont. (AP) — Montana Gov. Steve Bullock has ordered flags in the state to be flown at half-staff to honor former Supreme Court Justice John Paul Stevens.

Flags are to be lowered Tuesday in memory of Stevens, who died earlier this month at age 99.

A ceremony was held Monday at the court where Stevens served for nearly 35 years. He is to be buried Tuesday at Arlington National Cemetery in Virginia.

In his proclamation, Bullock said Stevens oversaw historic decisions regarding civil liberties, individual rights and holding the government accountable.

Bullock also noted that Stevens dissented against the court’s Citizens United decision that allowed corporate spending in elections. Bullock has made opposition to the ruling one his key campaign messages as he seeks the Democratic presidential nomination.