Three women have filed a class action accusing Google of systematically paying women less for the same work as men. They also say the tech giant keeps women largely partitioned into jobs where they are less likely to be promoted, promotes far fewer women than men despite similar qualifications, and moves women up the career ladder more slowly than men.

The U.S. Department of Labor is already investigating Google for discrimination against women in hiring. The DOL’s regional director has testified in federal court that the company engages in “systemic compensation disparities against women pretty much across the entire workforce.”

A mandatory audit by the DOL resulted in a startling statistical analysis. “The Office of Federal Contract Compliance Program’s analysis found six to seven standard deviations between pay for men and women in nearly every job classification in 2015,” points out the class action. “Two standard deviations is considered statistically significant; six or seven standard deviations means there is a one in a million chance that the disparity is occurring randomly or by chance.”

The three women believe their experiences with career partitions and lack of advancement are representative of Google women’s experiences generally, so they are seeking class action certification.

Each of their experiences is different, and a detailed account can be found in this article by the Courthouse News Service. We’ll just summarize one of their stories.

One of the women ended up a Google employee in 2012 when the tech giant bought out the company she worked for. Despite 2-1/2 years of experience in sales, she was assigned to a Level 2 sales position. Men with the same experience or less were assigned to Level 3.

She was also assigned to the “Sales Enabler” career ladder rather than the more lucrative Sales career ladder, which limited her ability to move upward and through the company.

“Almost all of the employees on the Sales teams [she] worked with were men,” the lawsuit claims. “About 50 percent of the employees she encountered with Sales Enablement jobs, however, were women.”

She ultimately decided that a Sales Enabler role would not allow her to receive just compensation for her output and skill level, so she resigned from Google in 2015.

Google denies the central allegations of the lawsuit, namely systematic discrimination in pay and advancement opportunities. It also vehemently denies the results of the Office of Federal Contract Compliance Program’s statistical analysis. It claims to perform its own annual audits which demonstrate no pay gap.

The three women claim violations of the California Equal Pay Act, the Fair Employment and Housing Act, the California Labor Code and other laws. They are seeking back wages and interest, restitution and damages.