Minn. Couples Challenge Marriage Ban

Three same-sex couples who tried to marry in Minnesota last March are suing their state over the constitutionality of its gay marriage ban.

The couples -- Duane Gajewski and Doug Benson; Lindzi Campbell and Jesse Dykhuis; John Rittman and Tom Trisko -- will file their lawsuit in the Hennepin County district court, according to the Minneapolis-St. Paul Star Tribune.

Their suit argues that the law should be nullified because it violates the "single subject" rule of the Minnesota constitution, which states that each law may have no more than one subject. However, the marriage equality ban, which became law in 1997, is included in a broader bill.