These unions have been established in a number of countries since the late 1990s, often developing from less formal domestic partnership legislation.
In Denmark, Iceland, Norway and Sweden, they have since been replaced, and in a number of other countries supplemented, by same-sex marriage.
Supporters of same-sex marriage contend that treating same-sex couples differently from other couples under the law allows for inferior treatment and that if civil unions were the same as marriage there would be no reason for two separate laws.
A New Jersey commission which reviewed the state's civil union law reported that the law "invites and encourages unequal treatment of same-sex couples and their children".
There's no good reason to do that." However, some opponents of same-sex marriage claim that civil unions rob marriage of its unique status; Randy Thomasson, Executive Director of the Campaign for California Families, calls civil unions "homosexual marriage by another name" and contends that civil unions provide same-sex couples "all the rights of marriage available under state law." in state law.