The labor cases I've seen won are cases involving not paying/promoting minorities/women equally. When you have a person who has the same educational background, experience, and hours worked as someone else but isn't getting paid the same one else, you can make a case for equal pay and likely win, even though none of that means that you are good worker. Ellen Pao's case looked strong, but there was a strong paper trail proving she was incompetent, and thus did not deserve equal pay/promotions. Without that paper trail, she would have won that case. Who can argue that she shouldn't have a senior role with her impeccable educational background and the fact that she probably worked the same number of hours as anybody else.
In this scenario, I doubt there is paper trail. Saying that you have an entire department that's mostly Indian/Chinese means nothing. There has to something definitive that says that QC prefers hiring Asians over others. Hiring H1B's over others is a stronger case.