Well, I sure don't see any legal basis for pursuing a claim against the employer or using it as leverage to get her to act more reasonably.
Under the employment at will doctrine, the employer is permitted to set the terms of employment, even if they are unreasonable unfortunately, as long as they do not violate specific laws (such as anti-discrimination laws) and they are not violating an employee contract.
While the conduct by the employer does appear to be severely damaging employee morale, it is likely not to the benefit of the company in the long-term, there would not typically be a legal violation here.
Having said that, employers often do become more reasonable if an employee retains an attorney, to prevent the possibility of a lawsuit being filed. So if you are serious about trying to get the work environment improved, I would consult further with a local attorney about communicating with the employer.
They do run the risk of a lawsuit being filed for defamation or other possible claims if they make false statements against employees, so that could form the basis of a warning/demand from the attorney, if the employer is making false statements about employees to others.
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