The Free Press and the Detroit News announced their joint-operating agreement on April 14, 1986.
The deal, which required federal approval, took effect about three and half years later on Nov. 27, 1989, after it went all the way to the U.S. Supreme Court.
At that time, the Free Press was owned by Knight Ridder and the News was owned by Gannett. Today, Gannett owns the Free Press, and MediaNews Group owns the News.
Source : Zlati Meyer, This Week In Michigan History, Detroit Free Press, April 14, 2013.