Armstrong Teasdale has defeated a former equity partner’s age bias lawsuit challenging the firm’s mandatory retirement age, with a Missouri federal judge ruling that the partner couldn’t claim to be an “employee” under a federal anti-discrimination law because he had already made a similar argument in state court and lost.

U.S. District Judge Henry Edward Autrey in St. Louis, who last year denied Armstrong Teasdale’s early attempt to dismiss former partner Joseph von Kaenel’s age bias suit, has now determined that the law firm deserves a judgment on the pleadings. The decision comes in a suit alleging von Kaenel was unfairly pushed out in 2014 under a mandate that partners retire from Armstrong Teasdale at the end of the calendar year in which they turn 70.

Autrey initially granted the Am Law 200 firm’s motion for judgment on the pleadings on Monday, then issued an amended opinion on Tuesday. In the decision, the judge noted that von Kaenel had previously litigated in state court the question of whether he could invoke a Missouri anti-discrimination law. After an evidentiary hearing in state court, a judge eventually ruled that von Kaenel couldn’t continue pressing his state claim because, as an equity partner and part owner of Armstrong Teasdale, he was not an “employee” as defined in the Missouri anti-bias law.

Von Kaenel’s federal suit, which was brought under the federal Age Discrimination in Employment Act, would also hinge on the question of whether he qualified as the kind of “employee” that the law is intended to protect, Autrey wrote in Tuesday’s opinion. Since that question was already litigated in the state court and von Kaenel lost, Autrey concluded that the former Armstrong Teasdale partner shouldn’t be able to continue his ADEA lawsuit.

“The Cole County court’s determination that plaintiff, as an equity partner of defendant, was not an ‘employee’ covered by Missouri’s anti-discrimination statute is binding on this litigation,” Autrey wrote. “As the ADEA only applies to employees, plaintiff’s claim necessarily fails.”

Neal Perryman of Lewis Rice, who represented Armstrong Teasdale, said “we are happy with the court’s ruling” but declined to comment further.

Gregory Rich of Dobson, Goldberg, Berns & Rich, who represented von Kaenel in the age bias litigation, did not immediately respond to a request for comment.

Von Kaenel is now of counsel at Evans & Dixon in St. Louis, working in the firm’s transactional practice.

The former Armstrong Teasdale partner’s complaint, initially filed in September 2016, asserted that the firm’s mandatory retirement policy entitled partners to two years of severance pay as long as the outgoing lawyer doesn’t continue in private practice. If the firm didn’t have the retirement policy, von Kaenel alleged, he could have continued practicing until he was 75 and collected the severance after that.

Armstrong Teasdale is not the first law firm to grapple with age bias claims over a mandatory retirement policy. In one notable case more than a decade ago, the U.S. Equal Employment Opportunity Commission pursued claims on behalf of a group of former Sidley Austin partners allegedly demoted in light of that firm’s mandatory retirement policy.

Sidley ended up resolving that suit in 2007 with a $27.5 million settlement in which it did not admit to any wrongdoing.