Steelplate
Employers don't have the right to do whatever they want.
Rose Captain
Technically, they do.
While employers often have the right to fire you, or to ask you to do things you might think are not in your job description, in general they can't ask you to do illegal acts, they can't discriminate, they can't harass you, they have to follow the labor laws for your state, they have to pay you OT if it aplies, etc. Or maybe I should phrase it as they can do that last set of things, but they will lose in court or at the NLRB.
Minor case in point - my company (headquartered in a different state) changed its vacation policy, which would have meant California employees could no longer "hold over" vacation from one year to the next - it became a "use it or lose it" policy. Once some employees pointed out this was illegal under California law, the policy was changed for employees in California. Rest of the company is under a "use it or lose it" policy, California employees aren't.
So no, employers can't do anything they want. But yes, they can fire you (in a right to work state) and suing them won't work if you can't prove discrimination (although age discrimination is just about impossible to prove).
The original context of this (if I've done my research correctly -it's on page 1 of this thread) had to do with an employer being able to cut pay by 30% if they disagreed with what one said in public. Or that employers can apply punishments as they see fit. Well, no - if you have agreed to do a job for a certain pay, they can't just cut it. They can move you to a different job, perhaps, that pays less (although even that is difficult if the employee didn't apply for the lesser paid job); but just suddenly cutting pay will probably not work. Neither will locking you in a closet (well, maybe if you're a teacher who has messed up but can't be fired...but they call it an office) or making you do pushups (if you aren't in the army). Can they fire you and not tell you why? sure. Can they fire you and tell you why and get away with it in some cases? sure - there are jobs - journalist, military, etc where you cannot express your position publicly.
But overall, employers can't do "anything". There are limits.
And thank goodness for the unions who helped arrive at these limits!