In general, once a separation agreement is signed, you cannot sue your employer for any reason. I strongly recommend having an attorney review any legal document before you sign.
Most severance agreements are pretty broad and will generally waive all your rights to file any complaint or claim against your former employer. If you are considering signing such an agreement you should have a local employment attorney review the agreement first, especially if you believe that your employer may have violated your rights. You can search for an attorney on Avvo or contact the National Employment Lawyers Association for a referral.
This answer is provided for guidance only. DO NOT rely on it as legal advice. We DO NOT have an attorney-client relationship. You should contact an attorney in your area for a one-on-one consultation before pursuing any action or making any decisions.
There is not true limit as to what the employer can ask for, but certain waivers of rare items are probably not enforceable. That being said, you will never know your rights unless you meet with an experienced employment attorney and have he or she review the agreement in question.
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