Military Spouses Equal Treatment Act - Considers a person a spouse, for purposes of military personnel policies and military and veterans' benefits, if the marriage of the individual is valid in the state in which the marriage was entered into or, in the case of a marriage entered into outside any state, if the marriage is valid in the place in which the marriage was entered into and the marriage could have been entered into in a state. Includes as a state the District of Columbia, the Commonwealths of Puerto Rico and the Northern Mariana Islands, and U.S. territories and possessions.