Michael J. Fox is returning to TV, this time behind the scenes, and Angie Harmon is leaving “Law & Order” after three years. First, Fox: Variety reports that the former star of “Spin City” is putting on his executive producer’s cap and developing a Lifetime cable network series based on author Suzanne Finnamore’s quirky romance “Otherwise Engaged,” which follows a married couple from the time of their engagement. A 2002 debut is expected. Fox, 39, left “Spin City” at the end of last season to dedicate his time to the fighting of Parkinson’s disease, from which he suffers. As for Harmon, who plays assistant D.A. Abbie Carmichael on the NBC drama, “She asked to be released early from her contractual commitment to the show,” “Law & Order” producer Dick Wolf told Variety. Harmon, 28, reportedly wants to focus on a movie career, though she will remain with the series through the end of this season. She may also surface in the first six episodes next season — given that producers plan to shoot extra segments of the show before a possible Screen Actors Guild strike this summer.