What is a civil union? A civil union is a legal relationship between two people that provides legal protections to the couple only at the state level. A civil union is not a marriage, though. Civil unions do not provide federal protections, benefits, or responsibilities to couples, and a civil union may not be recognized by all states. Civil unions, similar to domestic partnerships in some ways, were established primarily as an alternative for same-sex couples in states where marriage was unavailable.

While same-sex marriage is now legal in all states, following the Supreme Court's 2015 Obergefell v. Hodges ruling, many of them began with civil unions. Some states that legalized same-sex marriage prior to Obergefell converted civil unions to marriages.

Civil Union vs. Marriage

Generally speaking, there are three main differences between civil unions and marriages, both from a legal, as well as practical perspective:

• Portability: Since civil unions are not recognized by all states, such agreements are not always valid when couples cross state lines.
• Federal Benefits: States are able to grant only state rights and benefits to partners in civil unions. There is no right to federal benefits for those in a civil union, regardless of whether it's same-sex or opposite-sex.
• Terminology: "Marriage" is a term that conveys societal and cultural meaning, which is important to both proponents and opponents of gay marriage. It's less of an issue after the Obergefell ruling, since marriage is available to same-sex couples in all states.

Civil Unions Vary State by State

Not every state has a civil union statute on the books -- it falls to state legislatures to decide whether or not to take up the issue. In 1999, Vermont became the first state to enact civil unions in order to comply with a court ruling. However, each state's definition of a civil union may vary. In Illinois, for instance, a civil union is a legal relationship between two people that provides most of the legal obligations, protections and benefits that the law of Illinois grants to married couples.

But an Illinois civil union is not a marriage. A civil union there does not provide federal protections or responsibilities otherwise offered to married couples. Examples include Social Security survivors' and spousal benefits, immigration rights associated with marriage, and the right to file joint federal tax returns.

The state of Connecticut, on the other hand, began with civil unions and later expanded marriage to include same-sex couples. The state enacted a civil union law in 2005, and then in 2010, state lawmakers agreed to repeal prior marriage laws and fully replace them with genderless terminology. All references to marriage became fully gender-neutral.

Connecticut civil unions ceased to be provided in 2010 and existing civil unions were automatically converted into marriages. Same-sex marriages, civil unions and broad domestic partnerships from other jurisdictions are legally treated as marriages in the state.

Many states in New England (like Rhode Island, Vermont, and New Hampshire) have followed a similar path of initially having civil unions that were converted to marriages.

But what a civil union is and whether it continues to exist in its current legal incarnation, particularly since same-sex marriage is now an option in all states, remains to be seen. For more information, FindLaw's Same Sex Marriage section is a constantly-updated resource.

Have Additional Questions About Civil Unions? Contact an Attorney

Since civil unions were primarily legal workarounds for committed same-sex couples prior to federal recognition of equal marriage rights, the arrangement has largely lost its value. But if you're in a same-sex relationship and have specific questions about getting married, it's a good idea to contact a family law attorney in your area.