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This answer is provided for informational purposes only and should not be relied on as legal advice. You should be aware that no attorney-client relationship is established through this answer and none will be established without a personal consultation and the signing of an engagement agreement.
Sexual harassment in the workplace is unlawful. However, your employer must know that it happened or is happening before they have a duty to investigate it and make it stop. You have an affirmative obligation to tell him to stop touching you and to report it to the owner/human resources dept., etc. If you report it and it doesn't stop - then you may have a case. It doesn't help that you have put up with the inappropriate touching by your manager for "a year" because he may think that it is ok with you that he touches your lower back, etc. You need to express yourself in a professional way, not by slapping him. Also, for sexual harassment to be unlawful, you have to have felt harassed and not invited or joined in the conduct. For example, if he touches your lower back and you smile or laugh, etc., it weakens any claim you may have. After you tell him not to touch you and report him - if the conduct continues, call an employment law attorney.
You may want to get as many of your co-workers, who are touched by your manager, to join in and substantiate your WRITTEN complaint to human resources. You should also ask the HR Department to save and review the video as evidence of the manager's unwanted touching. You should find out if any of your co-workers also complained or told the manager to stop, then speak with an attorney.
Let me offer you another perspective. This manager has been touching your lower back or waist for a year. You haven't told him not to do it, or that you don't like it. So since he's been doing it for a year, and you've never said anything, can you understand why he might think there's nothing wrong with what he's doing? and why he might have the impression that you don't object?
It's certainly true that the law doesn't require you to confront someone about sexual harassment before reporting him to HR. But before you affect someone's livelihood that way, please consider letting him know -- in a professional, non-physical way -- that his behavior is unwelcome and it needs to stop. Then if it doesn't change, you can approach his supervisor or HR, knowing that you gave him the opportunity to correct his behavior.
It's not legally required that you do this, but it sure seems like the decent thing to do before putting in jeopardy the job of someone who may not even know he's doing something you don't like.
Craig T. Byrnes
Disclaimer: Please be aware that I am not offering legal advice, nor forming an attorney-client relationship with you. I am not representing you, nor doing anything to protect your legal rights. If you believe that you have suffered a legal wrong, take action before any statute or limitations expires, or your right to do so may be lost forever. Good luck in your legal matter.
The other attorneys responding to your question have given you good advice, not the least of which is the need to document and see an attorney. Let me add one other point. Supervisors are strictly liable for misconduct in the workplace and the employer is also liable (vicariously liable) for the supervisor's misconduct. The Fair Employment & Housing Act holds an employer strictly liable for harassment by the aggrieved employee's direct supervisor or any other manager. Only as to harassment by other coworkers or employees, is the employer only liable if it (or its agents or supervisor) knew or should have known of this conduct and failed to take immediate and appropriate corrective action. [Gov.C. § 12940(j)(1).)
Thus, your employer is liable even if it did not know the conduct was occurring. And the fact that you did not complain does not make me feel sorry for the manager - he should know where his hands belong. Possible defenses include that the conduct did not offend you, that the conduct would not have offended the reasonable woman and the conduct was consensual. Based on your description, it seems to me the conduct was offensive, would be offensive to the average female server and was not consensual. You may have a claim. Witnesses would help immensely as would any other documentation. You should consult with an attorney right away. I'm sorry you have had to experience this at work and good luck to you.