This Tuesday, the Supreme Court will hear arguments regarding the biggest class-action discrimination lawsuit yet. At stake, in Wal-Mart v. Dukes, is whether a federal court may hear a nationwide class-action suit on behalf of nearly 1.5 million female Wal-Mart employees, charging the company with gender-based pay and promotion discrimination.

The question is whether all these women have enough in common to file a single lawsuit together.

The basis of the suit rests largely on 120 statements of anecdotal evidence, statistics on gender gaps in pay and promotion, and a statement by a Chicago sociologist on implicit bias.

Victoria Pynchon at Forbes blog, has this to offer on the question whether structural discrimination in the form of implicit biases should count as valid evidence in front of the high court:

The Supreme Court on Tuesday can narrow the discussion to the evidentiary question presented to it in a cultural vacuum or it can address the broader policy issue – whether the inability to prove the effects of implicit bias on a case-by-case basis should permit employees to use social science research to prove that the system itself is implicitly rigged against them.

Basically, Wal-Mart ought to pay because its managers may hold implicit biases against women, leading them to wrongfully discriminate against them in pay and promotion questions. We don’t know that all of these women were in fact subject to discrimination, but merely by the fact that they were women, we’re pretty confident that they probably were.

Could lofty evidence like this justify billions of dollars in damages, and far-reaching consequences for women workers everywhere?

What will happen if the Supreme Justices rule against Wal-Mart is that the use of statistics to justify claims of gender-based discrimination will receive a whole new meaning. If we can agree that women in general suffer from structural discrimination, and it can be shown that a company has significant gender gaps in pay and promotion statistics, bam (!) you’ve got your class action suit. No additional evidence needed. Clearly, if you’re a woman you are being discriminated against.

In order to avoid frivolous lawsuits based on this dangerous precedent set by the Wal-Mart case, other businesses will likely implement more rigid hiring policies, no longer affording women the much needed job flexibility they so desperately need in order to combine their work and family responsibilities.

The main reasons for why women earn less than men on average are that they take more time off from work to care for family members, they work fewer hours, and choose different, often times lower-paying, occupations that are less demanding on their schedules. As Carrie Lukas stated with respect to the Wal-Mart case:

Even if statistics show that men and women earn different amounts, discrimination isn’t necessarily to blame.

Furthermore, hiring women will become a lot more expensive because the associated legal risks go way up. Businesses are run by people and people respond to incentives. If you make it more expensive to hire women, fewer women will be hired. A store like Wal-Mart may put in place more self-checkout machines, instead of hiring women cashiers, for example.

Low-income, less-educated women, who may be single moms, struggling to make ends meet, will bear the brunt of these consequences.