Legal marriage is a state-defined contract currently available only to a man and a woman. Every state has a different set of laws, numbering from 160 to more than 250. The U.S. Federal system has more than 1,040 laws which are triggered by legal marriage. These laws interface with almost every sphere of social interaction. They treat a family as a legal unit, which is especially important during times of change, such as divorce, or during a family crisis, such as the right for a spouse to make medical decisions.
Marriage laws allow for the understanding of the married couple as full adults in our culture.
Couples married by a state government are automatically granted a broad range of rights at the federal level. These rights affect federal employees such as civil servants and the military. For the purposes of nearly all of the above items, same-sex couples are considered legal strangers, and thereby unable to be covered by them. Ceremonial marriage may be officiated by church officials, or anyone you choose. Many churches marry same-sex couples.