Patent law allows a trial court to make the losing party pay the winner's attorneys' fees but only in "exceptional cases". 35 U.S.C. 285. What counts as "exceptional", you say? Good question.
The U.S. Supreme Court plans to answer it in Octane Fitness, LLC v. Icon Health & Fitness, Inc., No. 12-1184 (U.S.), which
If you wonder what "prosecution history estoppel" in a patent infringement case means, you might check out MarcTec, LLC v. Johnson & Johnson, No. 10-2085 (Fed. Cir. Jan. 3, 2012), in which the court affirmed an award of $4,683,653.03 in fees and expenses to the defendants.
MarcTec alleged infringement by the "Cypher stent" —