The balance of power between employers and employees is the result of years of public policy, lobbying and enough history to fill countless books. An abusive employer can make your life hell. Unless you are one of the fortunate few who can leave your job, totally confident of getting another just as good, you face a difficult decision in deciding when enough is enough. That decision might depend on your rights as a worker. In the United States, your rights likely fall far short of those in other nations. Employers face some restrictions, but it is important to understand what you need to show to win a battle in court.
The vast majority of workers in the U.S. are considered "at-will" employees. The "will" in question is that of the employer. Most people can be fired for trivial reasons, bad reasons, or even no reason at all. There are things that cannot form the basis of a termination, however. You cannot be fired for your age, race, gender, ethnicity or nation of origin. In New Jersey, you cannot be fired for your sexual orientation or your gender identity or expression. Of course, your employer is unlikely to be kind enough to put down in writing that you are being fired for getting too old or for being gay. The signs of bigotry, sexism, ageism and intolerance are often found in a history of conduct.
The United States is the only industrialized country where at-will employment is the norm. The power granted to employers here is astounding. Unsurprisingly, employers imbued with that sort of power occasionally abuse it. They refuse to pay overtime when workers deserve it. They deny employees the right to reasonable accommodations. They fire employees in retaliation for protected acts like asking for family medical leave or filing workers' compensation claims. In those cases, employers have gone too far and should be held accountable.
Source: The Boston Globe, "Tom Brady has more rights than most American workers," by Evan Horowitz, 31 August 2015