Sept 11 (Reuters) - A former government antitrust

enforcer who oversaw price-fixing cases for U.S. states against

major generic drugmakers should be barred from working on

similar matters at his private law firm, a group of

pharmaceutical companies told a federal judge on Wednesday.

In filings in federal court in Philadelphia, Pfizer ( PFE ), Teva,

Mylan and several other drugmakers said that the lawyer, Joseph

Nielsen, a former assistant Connecticut state attorney general,

and his law firm should be disqualified from representing

insurers Molina and Humana in ongoing antitrust litigation.

The companies claimed that Nielsen, who had worked for

Connecticut for nearly 20 years until July, acquired

confidential information while overseeing drug-price litigation

for the state against dozens of drug manufacturers.

Nielsen and his law firm Lowey Dannenberg, a small

plaintiffs-focused firm with offices in New York and

Pennsylvania, did not immediately respond to requests for

comment.

The Lowey firm told the defendants that Nielsen would not

share confidential information gained from past settlement

negotiations and that there were no restrictions on his

representation of Molina and Humana, the drugmakers said in

their court filings.

Nielsen's participation in the lawsuit runs afoul of rules

restricting the work of government lawyers who enter private

practice, the drugmakers alleged.

"He undoubtedly has unique insight into how defendants

assess the merits, value the claims, approach settlement

negotiations, and is able or unable to satisfy any judgment or

settlement demand," according to the drugmakers. "He cannot

unlearn any of that."

Pfizer ( PFE ), Teva and Mylan, now part of Viatris ( VTRS ), also did not

immediately respond to requests for comment.

Nielsen began representing Molina and Humana in July as a

newly-named partner at Lowey. The firm markets its work for

major insurers seeking damages for alleged overcharges for

prescription drugs.

The push to disqualify Nielsen and his firm comes after

Humana's lawsuit was selected last week by U.S. District Judge

Cynthia Rufe in Philadelphia as a bellwether case to test claims

against the drugmakers, and was set for trial in September 2026.

Rufe in an order on Thursday referred the drugmakers'

disqualification effort to a court official to prepare a report

and recommendation to the judge.

The case is In Re: Generic Pharmaceuticals Pricing Antitrust

Litigation, U.S. District Court for the Eastern District of

Pennsylvania, No. 2:20-cv-00695-CMR.

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