"I believe we should be allowed to marry the person we're in love with ... and we deserve the freedom to do so," plaintiff Marie Carlson said at a news conference, the Milwaukee Journal Sentinel reported. Her suit is supported by the American Civil Liberties Union.
"This constitutional amendment was approved by a large majority of Wisconsin residents," state Attorney General J.B. Van Hollen said in a statement. "I believe the amendment is constitutional, and I will vigorously defend it."
The ACLU's lawsuit argues Wisconsin's gay-marriage ban violates the U.S. Constitution's guarantee of due process and equal protection under the law. It also aims to overturn the state's so-called marriage evasion law, which makes it a crime to travel to another state to get married if that union would not be recognized by the Badger State.
Seventeen states and Washington, D.C., permit gay marriage.
Celebrity Families of 2014 [PHOTOS]