In addition to his speaking and teaching roles, Mueller also joined the law firm WilmerHale as a partner in its Washington office in 2014.[53] Among other roles at the firm, he oversaw the independent investigation into the NFL's conduct surrounding the video that appeared to show NFL player Ray Rice assaulting his fiancée.[54] In January 2016, he was appointed as Settlement Master in the U.S. consumer litigation over the Volkswagen emissions scandal; as of May 11, 2017, the scandal has resulted in $11.2 billion in customer settlements.[55]