And as always, even worse-- You won't ever know if you just aren't up to snuff as an engineer / interviewer or if one or more of your interviewers, recruiters or hiring agents knows of and/or participates in such "blacklisting"
Which is also illegal, but companies openly get away with it every day.
The worst that ever happens is a slap on the wrist when all the major companies have non recruitment ("no poaching") agreements with each other, suppress wages, get caught, and have to pay a token fine.
Those situations can often be solved in much the same way. If someone is giving out malicious references due to an enforcement action, you report it to the EEOC or other agencies. That is also a violation and can result in further action on your behalf. Many states have statutes on the books against blacklisting and you may be able to engage the state DOL or other agencies to help you. These agencies have the full weight of the federal or state government behind them and are not in the habit of losing enforcement actions.
This is not likely to be the case. It is not so easy to pursue a retaliation complaint. I suggest you look at the case law history here. America is not France where the courts almost always side with employees. It's just the opposite. There's a very high bar for retaliation complaints and it's getting higher all the time [1]. These days you basically need a confession from your employer to establish that the retaliation was the "determinative factor."
You left off a pretty important qualifier. If you're willing to entertain the fact that tech jobs exist outside of Silicon Valley, finding another equivalent job after winning a discrimination lawsuit against a former employer is no problem.
