A California appellate court has upheld a ruling denying class certification in a gender discrimination case brought on behalf of 135 women software engineers at Twitter who claim they were disproportionately passed over for promotion. 

In a 15-page unpublished decision, the First District Court of Appeal on Wednesday upheld an earlier ruling denying class certification in the case issued last year by San Francisco Superior Court Judge Mary Wiss. 

In her ruling last year, Wiss cited the U.S. Supreme Court's 2011 decision in Walmart Stores v. Dukes, which found a nationwide class of women employees at the retail chain was inappropriate since promotion and pay decisions were made by local managers without a common mandate from the company. 

On appeal plaintiffs lawyer Jason Lohr of San Francisco's Lohr Ripamonti & Segarich argued that Wiss had erroneously relied on Dukes, since California class action law departs at times from federal precedent. But First District Justice Barbara Jones noted in Wednesday's opinion that the plaintiff in the Twitter case had relied on Dukes in her own class certification motion.

"Because plaintiff invited the court to use Dukes, she cannot complain that the court accepted her invitation," Jones wrote.

The First District further affirmed Wiss' conclusion that the lead plaintiff, Tina Huang, one of the company's first female engineers, had claims that weren't typical to those of other proposed class members. Where the plaintiffs complained that Twitter managers' gate-keeping caused a disparate impact on women engineers seeking promotions, Huang actually had the backing of her manager during the promotion cycle when she was passed over. The appellate court also found that Twitter's promotion procedures varied over the class period and weren't uniformly followed by decision-makers.

"Where a policy is implemented various ways, the denial of class certification is not erroneous," Jones wrote.

Lohr said in an email Wednesday that he was "tremendously disappointed" with the outcome. "We will be reviewing the opinion in great detail and will make a determination regarding further review," he said.

Twitter was represented by outside counsel at Orrick, Herrington & Sutcliffe. "Twitter is pleased with today's ruling, and will continue to vigorously defend against the plaintiff's claims," a company spokesperson said via email. "We are deeply committed to an inclusive and diverse workplace, and to the fair and equitable treatment of all our employees."

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