The ACLU and gay rights group Lambda Legal will file a lawsuit in Cook County today arguing that the Cook County Clerk's Office violates the constitution's equal protection clause by not recognizing same sex marriage. The politics behind the lawsuit are interesting: Cook County Clerk David Orr is actually in complete support of same sex marriage, as is Gov. Pat Quinn.
However, the Illinois Marriage and Dissolution of Marriage Act prevents the state from marrying same sex couples, and a bill to legalize same marriage languishes in the Illinois House. It is not clear if Illinois will defend their current ban on same sex marriage in court.