If you receive a disciplinary warning, a criticism, a write-up at work, should you sign it? Yes, sign it. You are not confessing, you are not saying that “I admit to the bad performance” or whatever they are accusing you of. You are merely signing typically that you received it. If you don’t sign it they will simply say the employee refused to sign and file it.
Way more important than that is rebutting the write-up by saying it was discriminatory, if it was – if the unfairness is because of who you are, something about you that the law protects – your race, your age, because of a recent protected leave like a maternity leave, now you are being treated differently and being criticized unfairly. That’s illegal and when you complain about that your employer must investigate that, and not subject you to retaliatory backlash just because you’ve complain. That’s the way you strongly rebut and respond to an unfair discriminatory write-up at work. But go ahead and sign it, it doesn’t matter at all.