loyalty oath

:  a usually mandatory oath affirming the loyalty of its taker (as to a sovereign, government, or party principles) ruled the Genevese … with the help of loyalty oaths and the gibbet — Times Literary Supplement the loyalty oath will be abandoned at the next Democratic convention — Newsweek; especially :  an oath often required of public employees or applicants for public employment in the U.S. typically affirming that the signer upholds the U.S. or state constitutions and is not knowingly a member of any of a number of organizations held to be subversive