After Paula Patton just landed the biggest movie role of her career, the female lead in Mission: Impossible 4, she had to pull out of Law & Order: SVU where she was to play Assistant District Attorney Mikka Von. So now Melissa Sagemiller has been tapped to step in and recur as a new ADA on the show, which returns for a 12th season on Sept. 22. I hear the producers of the veteran NBC procedural from Wolf Films and UMS were gracious in allowing Patton to bow out after only one episode. Stephanie March was the last actress to play an ADA on the show full time. Last year, Sharon Stone and Christine Lahti both did high-profile multi-episode arcs as ADAs. Sagemiller’s series credits include Raising the Bar and Sleeper Cell.