RICHMOND, Va. (AP) — The Democratic attorneys general in the three states that ratified the Equal Rights Amendment long after a deadline set by Congress expired are set to unveil litigation over the proposed amendment to the U.S. Constitution.

Virginia Attorney General Mark Herring’s office announced Wednesday that he was partnering with fellow Democratic attorneys general Kwame Raoul of Illinois and Aaron Ford of Nevada on “landmark civil rights litigation concerning the Equal Rights Amendment.” A spokeswoman for Herring declined to give further comment on the lawsuit ahead of a press conference scheduled for Thursday.

Virginia earlier in the week became the critical 38th state to ratify the measure.