Gilead contends that there were better and more efficacious alternatives such as Viread® and another generic product that were on the doorstep of entering the market. As previously discussed, it is within the court's discretion whether or not to award attorney's fees. Machinery Corp. of Am., 774 F.2d at 471; Badalamenti v. Dunham's, Inc., 896 F.2d 1359, 1364 (Fed. Cir. 1990). It is equally clear that the defendant bears the burden of proving, by clear and convincing evidence, that this case is exceptional.