A legal contract designed to provide same-sex couples some of the rights, responsibilities and benefits of a marriage. The concept originated in Denmark in 1989 and has been adopted by many countries and U.S. states, staring with Vermont in 2000. Civil union laws vary on what is covered, and they have been criticized for not offering the identical or nearly identical rights as marriage. Civil unions also are have been criticized for as creating a separate (and unequal) legal status for gays and lesbians. Proponents say they offer solutions to legal issues involving property and health care for gay couples. Civil unions are sometimes referred to as domestic partnerships. In some places, they also are available to opposite-sex couples.