SAN FRANCISCO — Douglas Lumish is leaving the office he helped open in Silicon Valley for Kasowitz Benson Torres & Friedman. He and three other partners will join Latham & Watkins, three sources with direct knowledge of the matter said.

Lumish, who leads Kasowitz’s IP practice, will move to Latham with fellow IP litigation partners Jeffrey Homrig and Gabriel Gross, both based in Silicon Valley, and Michael Eisenberg, who is based in New York. The date of the partners’ move to Latham has not yet been determined due to their contractual obligations to Kasowitz.

"Doug Lumish and the three other attorneys have notified us that they will be departing," Kasowitz partner Aaron Marks wrote in an email. "Our firm represents, and will remain well-positioned to represent, clients in major patent litigation matters. We have outstanding IP litigators in California and in our other offices around the country who are providing, and will continue to provide, our patent clients with first-rate representation."

Lumish, Homrig and Gross are currently the only partners in the Palo Alto office. Recruiters have begun reaching out to IP litigators in the Valley about taking the reins at Kasowitz, said an IP partner who was approached.

"They are trying to give a compelling case to have people go and continue the office or start over," the partner said.

Lumish, who started his career at Weil, Gotshal & Manges, joined Kasowitz in January 2011 to help the firm carve out a presence in Silicon Valley. He told The Recorder at the time that he was eager to build an IP litigation practice that married the Valley’s entrepreneurial spirit with the depth of a national firm.

At Latham, Lumish will work with a deep bench like the one he enjoyed at Weil, legal watchers say. Latham added to its IP litigation bench in 2011 by recruiting six partners from Wilson Sonsini Goodrich & Rosati.

"By moving his team to Latham, [Lumish] once again creates a patent litigation team that is deep in talent," legal recruiter Martha Angell said.

"One would expect a real synergy between what Latham has done on the corporate side and what Doug and his team are doing on the patent litigation side," added Vernon Winters, an IP litigation partner at Sidley Austin who worked with Lumish at Weil.

Neither Lumish nor his partners responded to requests for comment. A Latham spokesman declined to comment on the move.