Twitter is being sued by a former female engineer who claims she was overlooked for promotion in favour of her male colleagues . Tina Huang 's proposed class action for sex discrimination comes as male-dominated Silicon Valley has been rocked by two other high profile lawsuits . In the complaint , filed in San Francisco on Thursday , Miss Huang has accused the microblogging site of discriminating against women in the way it promotes its employees . In the papers , she claims the firm has no formal procedure for posting job vacancies or granting promotions . Twitter is being sued by a former female engineer Tina Huang for gender discrimination . Instead , she says the company relies on a secretive 'shoulder tap ' process that allows few women to achieve the top engineering positions . In the legal papers Miss Huang allegedly argues that 79 per cent of Twitter 's leadership team is male , according to Mashable . Miss Hiss Huang complained to Twitter CEO Dick Costolo , pictured . Miss Hunag is one of Twitter 's oldest employees after joining the firm in October 2009 . She was put on leave after she raised a grievance with CEO Dick Costolo about her lack of promotion and quit in June 2014 . 'Despite being one of Twitter 's oldest employees , Ms. Huang 's career at Twitter was irreparably derailed for making a complaint , court documents says , according to Business Insider . 'After three months without explanation as to the status of the investigation , or mention of any possible time frame for her return to work , she felt she had no choice but to leave the company for the sake of her career . ' She is now seeking other employees at the firm who feel they have been passed over for promotion to join her in the lawsuit . A spokesman for Twitter said Miss Huang had resigned and was not forced out . 'Twitter is deeply committed to a diverse and supportive workplace , and we believe the facts will show Ms Huang was treated fairly , ' they said . Miss Huang started her legal action as the case was being heard of Ellen Pao , a former partner at venture capital firm Kleiner Perkins Caulfield and Byers , who is suing for sexual discrimination . During the high-profile trial in San Francisco she has claimed she was passed over for promotion because she is a woman . She alleges that she was fired in 2012 after she complained . The firm deny her claims of sexual discrimination and harassment . At the weekend a judge denied a request by lawyers for Kleiner Perkins Caufield & Byers to have Pao 's demand for unspecified punitive damages thrown out . Judge Harold Kahn said : 'There is sufficient evidence from which a reasonable juror could conclude that Kleiner Perkins engaged in intentional gender discrimination by failing to promote Ms. Pao and terminating her employment , ' the judge said in the one-paragraph decision . Pao can seek punitive damages that could add millions of dollars to a possible verdict in her favour . She is seeking $ 16 million in lost wages and bonuses . Meanwhile , Facebook is also facing a lawsuit from former employee and program manager Chia Hong . According to the complaint she has filed with San Mateo Court , she was belittled by her boss for taking time off to volunteer at her children 's school , forced to served drinks to male co-workers and told she should have just stayed home to take care of her child . Ellen Pao , a former partner at Kleiner Perkins Caufield & Byers , pictured left , and Chia Hong , a former Facebook employee , pictured right , have put the spot light on gender discrimination in Silicon Valley . A Facebook spokesperson denied the allegations and told Recode that the company has made progress in matters related to gender , diversity , and equality . 'In this case we have substantive disagreements on the facts , ' the spokesperson said 'and we believe the record shows the employee was treated fairly . '
Female engineer sue Huang is suing Twitter for gender discrimination . Claims she was overlooked for promotion in favor of male colleagues . currently the Silicon Valley firm has no formal procedure for promotions . And alleges there was a ' shoulder tap ' campaign that promotes diversity . Twitter says it is committed to diversity and that she was treated fairly . Comes as Silicon gets sued by two other high profile lawsuits .