Todd Warnken entered into a civil union with a man in Vermont in 2003. Without dissolving that relationship, he then married another man, Richard Elia, in Massachusetts in 2005, shortly after same-sex marriage became legal in that state. Was this a valid marriage? That depends on whether Massachusetts treats the civil union as a marriage for purposes of applying its bigamy laws, which prohibit a person with a living spouse from marrying another person.
In Elia-Warnken v. Elia, the Massachusetts Supreme Judicial Court ruled that civil unions from other states should be recognized, just as marriages are, on grounds of comity. This means that Todd’s marriage to Richard was bigamous and thus void from the very start.
Joanna L. Grossman,
Beware the Undissolved Civil Union: Massachusetts’ Highest Court Says That A Subsequent Marriage is Polygamy Verdict
Available at: https://scholarlycommons.law.hofstra.edu/faculty_scholarship/953