It's not a mistake, and it isn't severe. You're talking about exceptions to the law, not the law itself. The law is exercised thousands of times a day and wrongful termination lawsuits account for single-digit percentages.
As the plaintiff in such a case you need to be able to provide evidence that it's "reasonable to believe" that you were fired because of whatever protected class you fall into.
It can be difficult to do, especially if you're blindsided and escorted out of the building and cut off from any sort of evidence (tip: if you think you could be fired because of who you are, start keeping receipts before you're fired).
Previous to winning my own discrimination case, I was a juror in a case where an employer almost got away with blatantly discriminatory firing. They thought they were being sly by sacrificing another non-protected employee at the same time... but then bragged about it to an employee they didn't realize would rat them out. If it wasn't for that email there wouldn't have been enough evidence to know for sure.
That aside, if you're not a protected class (the majority of people aren't)... good luck. You can be fired without cause at any given moment.
As the plaintiff in such a case you need to be able to provide evidence that it's "reasonable to believe" that you were fired because of whatever protected class you fall into.
It can be difficult to do, especially if you're blindsided and escorted out of the building and cut off from any sort of evidence (tip: if you think you could be fired because of who you are, start keeping receipts before you're fired).
Previous to winning my own discrimination case, I was a juror in a case where an employer almost got away with blatantly discriminatory firing. They thought they were being sly by sacrificing another non-protected employee at the same time... but then bragged about it to an employee they didn't realize would rat them out. If it wasn't for that email there wouldn't have been enough evidence to know for sure.
That aside, if you're not a protected class (the majority of people aren't)... good luck. You can be fired without cause at any given moment.