In Uniloc v. Microsoft, the Federal Circuit ruled that the testimony of the expert witness Uniloc called to determine damages was inadmissible. With the 25 percent rule of thumb and other essentially arbitrary methods of calculation no longer acceptable in determining damages, experts say it may be wise to have witnesses prepare multiple damages theories.

“From here on out, district judges likely will scrutinize damages theories applied by experts to see whether they are nothing more than rules of thumb,” says Chris Renk, a shareholder at Banner & Witcoff. “You're likely to see experts compartmentalize their reports. They may have alternative theories, because if you have an expert who has one theory of damages and it gets excluded, you're in relatively significant trouble at trial because your expert can't testify at all.”