In another blow to Kirkland & Ellis’s intellectual property practice, partner Gerald Flattmann Jr., who specializes in pharmaceutical and biotech patent litigation, has told the firm he’s leaving for Paul, Hastings, Janofsky & Walker. In an interview Monday afternoon shortly after he tendered his resignation, Flattmann told the Litigation Daily that Kirkland IP partners Melanie Rupert and Christine Willgoos will also be joining him at Paul Hastings as of counsel.

Flattmann, who has represented pharmaceutical clients such as Forrest Laboratories and Sanofi-Aventis, is the third high-profile IP partner to leave Kirkland this year. In January, we broke the news that Kirkland IP star John Desmarais, one of the firm’s biggest rainmakers, was stepping down to start his own patent licensing company. His departure followed an announcement that Kirkland IP partner Peter Armenio had joined Quinn Emanuel Urquhart & Sullivan as co-chair of its life sciences team. (In January, Kirkland also lost rainmaker David Bernick, who joined Philip Morris International.)

Although Flattmann praised Kirkland in his interview with us, the 43-year-old told us his move was related to the previous departures of his onetime Kirkland IP colleagues. Like Flattmann, Desmarais and Armenio represented brand-name pharmaceutical companies in patent cases. In that specialty, Flattmann said, having breadth and depth at the partner level is key.

At Paul Hastings, Flattmann will be joining partners Bruce Wexler and Joseph O’Malley, who started the firm’s pharma IP practice four years ago as laterals from Fitzpatrick, Cella, Harper & Scinto. Flattmann described the group as having one of the elite branded pharmaceutical patent practices in the country. “I think you can do both [branded and generic IP litigation], but you can’t do both exceptionally well,” said Flattmann.

In a statement, O’Malley of Paul Hastings highlighted Flattmann’s work on behalf of brand-name pharmaceutical companies. “The biotech credentials of Gerald and his team, along with our lawyers’ successful track record against the generic pharmaceutical companies, will uniquely position the firm to assist branded pharmaceutical companies as their biotech products are challenged by the generics under the recent Health Care Reform Law,” the statement says.

Jay Lefkowitz, a senior litigation partner at Kirkland, said that the firm wishes Flattmann well.

This article originally appeared in The Am Law Litigation Daily.