SAN FRANCISCO — Hogan Lovells is bracing for a fight with a patent assertion entity it used to call a client.

The global law firm disclosed in court papers filed in the U.S. District Court for the Northern District of California that it has been threatened with a professional negligence suit seeking tens of millions in damages by Conversant Intellectual Property Management Inc., a Canadian company it represented in two patent suits.

Keker & Van Nest partner Elliot Peters launched a preemptive strike for Hogan Lovells on Tuesday, suing to obtain an order that any dispute between the firm and its former client must be hashed out in arbitration.

Upon hiring Hogan, Conversant signed a retainer agreement waiving its right to a jury trial over the firm’s services, Peters noted in court papers. He suggested that the serial patent plaintiff should know better than to try to walk away from such a contract.

“Conversant is no stranger to dealing with outside counsel and participating in litigation,” he wrote in the petition to compel arbitration.

Neither Peters nor a spokesman for Hogan Lovells responded to requests for comment about Hogan Lovells v. Conversant, 14-2206. Conversant lawyer William Reid of Reid Collins & Tsai in New York declined to comment.

Court papers outline Hogan Lovells’ falling out with the Ottawa-based patent assertion entity. In 2010, Cisco Systems Inc. filed for declaratory judgment in Delaware federal court, stating that its modem products did not infringe 10 patents owned by Conversant, then known as Mosaid Technologies Inc.

Conversant hired several partners at now-defunct Howrey to defend it, and they brought the work with them to Hogan Lovells when they joined the firm’s San Francisco office in 2011. Later that year, Hogan Lovells asserted six of the patents for Conversant before the International Trade Commission in a case that has since settled.

The team was led by K.T. “Sunny” Cherian, previously cohead of Hogan Lovells’ intellecutal property litigation practice, and included partners Scott Wales and Sarah Jalali. Cherian and Wales recently left Hogan Lovells for Winston & Strawn. Cherian could not be reached for comment late Wednesday afternoon.

In 2012, Conversant terminated Hogan Lovells as counsel, replacing the lawyers with a team from Mayer Brown. Cisco subsequently filed an amended complaint accusing Conversant of improperly enticing third-party licensees to provide evidence in support of its arguments before the ITC. Cisco also alleged that Conversant failed to preserve documentary evidence from SercoNet Ltd., which sold the asserted patents.

Shortly before its executives were scheduled to be deposed, Conversant struck a settlement with Cisco to end the Delaware suit. But before the case was formally dismissed, Conversant lawyer Reid notified Hogan Lovells that the patent assertion entity planned to file a professional negligence suit against the firm based on its work for the company in Delaware and before the ITC. In addition to seeking millions of dollars in damages, Reid stated that Hogan Lovells also intended to claw back fees, according to court papers.

“Over the course of multiple discussions, Mr. Reid made clear that Conversant intends to file a complaint against Hogan Lovells in court, unless a resolution can be reached, despite his awareness of the signed retainer agreement and arbitration clause,” Peters stated.

Conversant has yet to respond to Hogan Lovells’ petition. The firm also maintains that Conversant’s claims are barred by the statute of limitations, according to court papers.

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