Twitter Inc. is facing a class action gender discrimination lawsuit, filed last Thursday in the California State court in San Francisco. A former female software engineer, Tina Huang, claims the company’s promotion process is unlawful and favors men. Secret management committees apparently make the promotion decisions, without considering job postings or reviews. According to Huang, this has led to overwhelming gender imbalance in the technical workforce of Twitter.

Mashable obtained text from the lawsuit, which explains how hiring decisions are the responsibility of a largely male upper management:

“Promotion into Twitter’s senior technical positions is based on subjective judgments, by committees that are comprised of and dependent on upper management at Twitter, and predominantly male. These judgments are tainted with conscious or unconscious prejudices and gender-based stereotypes, which explains why so few women employees at Twitter advance to senior and leadership positions.”

Tina Huang started at Twitter in 2009 and worked in various software engineering roles. After being overlooked for a promotion to Senior Staff Engineer, she ultimately left the company in June last year.

Prior to leaving Twitter, Huang claims that she emailed Twitter CEO Dick Costolo on March 3, 2014, highlighting her concerns over the promotion process. She was immediately placed on three months leave, while the company conducted an investigation. She resigned in June after receiving no details about the status of the investigation or a timeframe of when she would be able to return to work.

The class-action lawsuit is looking to end Twitter’s discriminatory practices and policies on behalf of all “similarly situated current and former female Twitter employees.” Huang charges that:

“Twitter discriminates against its female employees by failing to promote equally qualified or better-qualified women to engineering leadership positions. The company’s promotion system creates a glass ceiling for women that cannot be explained or justified by any reasonable business purpose, because Twitter has no meaningful promotion process for these jobs.”

A Twitter spokesman told Mashable on Friday that, “Ms. Huang resigned voluntarily from Twitter after our leadership tried to persuade her to stay. She was not fired. Twitter is deeply committed to a diverse and supportive workplace, and we believe the facts will show Ms. Huang was treated fairly.”

Twitter’s lawsuit comes just a few days after news broke about a sexual discrimination lawsuit that Facebook are facing in a San Mateo court. Chia Hong, claims her IT manager discriminated against her based on her sex and race. She also claims she faced prejudice after filing a discrimination complaint during her employment.

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