EMI Group companies sued online music industry executive Michael Robertson for copyright infringement, some seven years after his former company paid recording firms more than $100 million to settle a similar case. Several EMI-owned labels and publishers sued Robertson and MP3tunes LLC, which runs www.sideload.com and www.mp3tunes.com, for willful infringement of copyright over the Internet, according to a complaint filed in U.S. District Court in Manhattan.