CHICAGO (AP) _ Illinois has joined a group of states filing arguments with the U.S. Supreme Court that the Constitution requires approval of same-sex marriage nationwide.

The brief was filed in connection with challenges of state laws in Kentucky, Michigan, Ohio and Tennessee that ban same-sex couples from marrying and refuse to recognize such marriages sanctioned by other states. The high court will hear oral arguments about those cases April 28.

Attorney General Lisa Madigan said Friday that the right of same-sex marriage is to ensure everyone has equal protection of the laws and to affirm that ``all individuals are equal.''

The friend-of-the-court brief the states filed says refusal to recognize same-sex marriage harms the couples seeking it and their families. Non-recognition affects their decisions about education, employment, residency and more.