In the letter Madigan wrote "current Illinois restrictions against same-sex marriage violate the equal protection rights that belong to all citizens under the United States Constitution."
Madigan also argued in the letter that other counties are not required to follow the Coleman ruling but that she expected it "to be persuasive" to courts reviewing cases involving same-sex marriage licenses, according to The Chicago Tribune.
Not every county plans to issue marriage licenses immediately though. Officials for Lake County said they did not plan to start issuing same-sex marriage licenses before the June 1 deadline.
Read Madigan's letter here, via the Capitol Fax Blog.