The American Civil Liberties Union and LGBT organization Lambda Legal will file lawsuits Wednesday to bring same-sex marriage to Illinois, the Associated Press reported.

Representing more than two dozen gay and lesbian couples, the lawsuits will challenge a 1996 state law banning same-sex marriage for violating the state Constitution's equality and due process clauses, according to the AP. Illinois currently allows civil unions that fall short of providing the same rights as married couples.

Should the Illinois Supreme Court ultimately back the couples, the state would be the fourth to legalize same-sex marriage through the court system, following Massachusetts, Connecticut and Iowa. Six states and Washington, D.C., allow same-sex marriage, while laws in several states that opened marriage to gays and lesbians have yet to take effect.