U S Capitol Police Challenge Coin w/ Presentation Box. Fast Shipping. This is a great looking Capitol Police challenge coin. Coin is gold plated and about 1 9/16" in diameter and raised lettering on both sides with a reeded edge. Reverse side has St. Michael the Protector, Patron Saint of Law Enforcement and the words "In God We Trust". Coin is contained in an acrylic air tight holder and displayed in an attractive blue presentation box which will make this a very impressive gift or presentation. The United States Capitol Police is a federal law enforcement agency in the United States charged with protecting the United States Congress within the District of Columbia and throughout the United States and its territories. It answers to Congress, not the president of the United States, and is the only full-service federal law enforcement agency responsible to the legislative branch of the Federal Government of the United States.