In an infringement case, a Delaware federal judge has ruled that a lawyer’s patent prosecution work for the plaintiff 15 years ago doesn’t disqualify him from representing one of the defendants.

On Nov. 21, Judge Richard Andrews of the District of Delaware denied Walker Digital LLC’s motion to disqualify Stroock & Stroock & Lavan partner Ian DiBernardo from representing defendant On-Net Surveillance Systems Inc.

In June 2011, Walker Digital filed the case, Walker Digital LLC v. Axis Communications AB, 11-cv-558, against Axis and its U.S. subsidiary, On-Net Surveillance, for alleged infringement of four patents for an “Internet Surveillance System and Method.” Another defendant, Tyco Safety Products U.S. Inc., was dismissed from the case in January.

DiBernardo did some patent work for Walker Digital during his tenure at the now-defunct intellectual property boutique Morgan & Finnegan in the late 1990s.

Andrews’ order noted that DiBernardo’s work for Walker Digital included preparing draft patent applications and responses to the patent office. He wrote that DiBernardo “did not work on any of the patents in suit, on any patents related to the patents-in-suit, or on any Walker Digital patents directed to video surveillance technology.”

Andrews determined that “Mr. DiBernardo’s work was confined to junior prosecution work on patents unrelated to those in suit, either by specification or by subject matter.

There is no evidence that Mr. DiBernardo was involved in any discussions of Walker Digital’s strategies for patent prosecution, claim drafting, or licensing/litigation monetization of their patents.”

Even assuming that DiBernardo learned of Walker Digital’s general patent prosecution or claim drafting strategies from more senior attorneys, Andrews wrote, “it is not apparent at all how confidential knowledge of Walker Digital’s strategies and plans fifteen years ago could be relevant to any issue in this case, or harmful to [plaintiff] in some other way.”

Walker Digital’s lawyers at Bayard of Wilmington, Del. declined to comment.

None of On-Net’s counsel, including DiBernardo, other Stroock lawyers and Wilmington’s Potter Anderson & Corroon, responded to a request for comment,

Potter Anderson lawyers who represented Axis also did not respond. Axis’ lawyers at Philadelphia intellectual property boutique Volpe and Koenig declined to comment.

Michael Albert, a partner at Boston-based Wolf, Greenfield & Sacks who isn’t involved in the case, said that a party who tries to disqualify the other side’s lawyer or firm, needs to show more than just the fact that the lawyer or firm once represented the opposing party.

DiBernardo’s work at Morgan & Finnegan, where he began his career out of law school, provided only minimal exposure to Walker Digital’s confidential information, said Albert: “As Judge Andrews pointed out, any exposure to generalized confidences on the attorney’s part would have occurred over a decade earlier, so the information would not be likely to be current or even relevant to any issue in the present case.”