One Flag for All Act This bill prohibits the display of flags other than the flag of the United States in public buildings, military installations, and U.S. embassies or consulates. Excepted flags include: the National League of Families POW/MIA flag; flags representing the nation of a visiting diplomat; the state flag of a Member of Congress, outside or within the Member's office; flags representing a unit or branch of the Armed Forces, on military installations; any flag representing an Indian tribe; and any flag representing the state, territory, county, city, or local jurisdiction where the public building is located.