This is a major case under Rules 1.9 and 1.7. I and several other legal ethics professors submitted expert affidavits in support of 3M's motion.
http://minnlawyer.com/minnlawyerblog/2012/10/12/judge-disqualifies-covington-in-3m-lawsuit/
the court's decision is here:
http://images.abajournal.com/main_images/order.pdf