All Coast Guard Petty Officers and Commisioned Officers are considered "Federal Law Enforcement Officer's" but there authority to carry firearms, make arrests and such are very very restricted and are more a function of the assignment they are given at the time and less function of who they are. Example, a boarding officer on duty, on patrol vs. the same person walking home from duty.
Military Police have what is called authority, but not juristdiction over civilians. This was explained to me that they can give you a ticket and arrest you (authority) but must turn you over to civilian law enforement and courts as they lack jusristdiction.