Am Law 100 firm Locke Lord and a Dallas partner are facing a $30 million lawsuit by a former client who alleges the firm breached its duties in an underlying case where the client lost a $340 million verdict on appeal.

Retractable Technologies Inc., a Denton County-based medical device company, hired Locke Lord and partner Roy Hardin for representation in disputes with a competitor, according to the Nov. 7 original petition in Retractable Technologies v. Locke Lord.

The defendants did not disclose conflicts of interest, and they put their own financial interests over the client's, the petition said. The complaint does not elaborate, providing no details about the alleged conflict of interest. But if Retractable had known about the defendants' conflicts, it would have terminated the representation, according to the petition, which calls the plaintiff "RTI."

"Defendants improperly benefited from their breaches of fiduciary duty to the tune of more than $30 million [], paid to defendants by RTI for their representation of RTI in the underlying litigation and in other litigation," alleged the petition. "Additionally, defendants intentionally overbilled and falsified their billing in the underlying litigation."

Locke Lord spokeswoman Julie Gilbert wrote in an email, "These allegations are meritless and we will vigorously defend ourselves."

Retractable's attorney, Frank Hill, declined to comment when asked for more details on the defendants' alleged conflict of interest and overbilling.

"I don't feel comfortable talking publicly about it," he said. "We typically don't try these cases very much in the press."

Retractable also alleges the firm and attorney committed malpractice and were negligent when they convinced the company to follow a legal theory that had been rejected under applicable law. The defendants didn't explain that the legal theory was untenable, the petition said.

"Moreover, defendants failed to present relevant witnesses on one or more central issues in the case during the underlying litigation, which was fatal to RTI's claims," the petition said.

Read about the litigation:

Fifth Circuit Scraps $340M EDTX Antitrust Verdict

The plaintiff is suing for breach of fiduciary duty, legal malpractice and negligence. It seeks fee disgorgement, actual damages of more than $30 million, exemplary damages, attorney fees and costs and pre- and postjudgment interest.

Texas Lawyer reported previously that Locke Lord and Hardin represented Retractable in a  case that ended with the competitor, Becton Dickinson & Co., paying a $100 million settlement in 2004 over antitrust and product disparagement claims. Retractable sued again for patent infringement three years later and won a $5 million award in 2010 from Becton Dickinson.

Then in 2013, the company filed an antitrust case that was based on the patent infringement, among other claims. This time, Retractable won $340 million, but it was yanked away when the U.S. Court of Appeals for the Fifth Circuit determined in 2016 that patent infringement cannot give rise to antitrust liability.

Hardin didn't immediately return a call or email seeking comment. Neither did Locke Lord Dallas managing partner Vicky Gunning, nor firm spokeswoman Kristen Bugaris of Chicago.

Read the petition: