In the latest flare-up of a fierce trade secrets fight pitting Quinn Emanuel Urquhart & Sullivan against a new boutique formed by firm alumni, a federal judge in Los Angeles handed a small victory to the upstarts at Pierce Sergenian.

On Friday, U.S. District Judge Stephen Wilson disqualified one of Quinn Emanuel's proposed expert witnesses for crossing a “bright line”—she changed sides in the middle of the lawsuit.

“We viewed it as a pretty brazen move,” Pierce Sergenian name partner John Pierce said, adding that he found it “very poetic that our first big case is up against our former colleagues and mentors.” Four of the firm's seven lawyers, including co-founder David Sergenian, at some point worked at Quinn Emanuel.