 Upon the rise of the same-sex marriage movement in the early 1970s, Maryland established the first law in the United States that expressly defined marriage to be a union between a man and a woman.Attempts to both ban and legalize same-sex marriage in the 1990s and 2000s failed to gain enough support from central committees of the state legislature.Roman Catholic authorities throughout the state were adamantly opposed to the legalization of same-sex marriage, saying it deeply conflicted with the best interests of society and would threaten religious liberty.