Winston & Strawn on Monday lost its bid in the U.S. Supreme Court to stop a California state ruling that allowed a former partner to bring discrimination and retaliation claims in court against the law firm.

The former San Francisco-based partner, Constance Ramos, has resisted Winston & Strawn's push to keep her claims from being aired in public court. A California state appeals court last year set aside an arbitration provision in the firm's employment contract, a ruling the firm challenged in the high court.

Ramos has alleged she was unfairly passed over for work and effectively forced out of the law firm. Ramos now works at her own firm, Akira IP. Winston & Strawn's petition arrived at the high court at a time when more Big Law firms are facing claims of discrimination from female lawyers.

Business advocates and one major firm, Ropes & Gray, had filed an amicus brief urging the Supreme Court to review Winston & Strawn's petition.

"Today, it is common for law firms to experience regular fluctuations in their partnership ranks," Ropes & Gray partner Douglas Hallward-Driemeier wrote in the amicus brief. "As a result, it has become increasingly important for law firms to be able to quickly and efficiently resolve internal disputes in a way that protects confidential information and minimizes disruptions to client service."

Winston & Strawn, represented by Orrick, Herrington & Sutcliffe, had pitched the case as a new chance for the justices to confront issues that "are tremendously consequential to employers with a California presence."

Central to the petition was the 2000 California state court decision in Armendariz v. Foundation Health Psychcare Services, which found an arbitration agreement unenforceable because it didn't meet certain conditions.

Orrick partner E. Joshua Rosenkranz, lead counsel for Winston & Strawn, told the Supreme Court that Ramos' win "is emblematic of California courts' adherence to the overtly arbitration-disfavoring rules" that were established in the Armendariz decision.

Ramos' lawyer, Karla Gilbride of Public Justice, told the justices that Ramos would have won her challenge irrespective of the Armendariz ruling.

Gilbride, who had urged the justices to uphold Ramos' California state court win, said Winston & Strawn's "overly harsh" terms in the firm's partnership agreement drove the California state ruling against the law firm.

The scope of the Winston & Strawn arbitration provision, Gilbride argued, "would make it impossible for the arbitrators to award Ramos back pay, front pay, reinstatement or punitive damages—essentially every form of relief she sought in her complaint for employment discrimination and retaliation."