If being attacked in public by punches, what rights do I have to defend myself?

You do have the right to defend yourself, but may wind up hiring a criminal defense attorney and appearing in a court of law for stabbing someone.  You can never be sure that a stab wound would not hit a major artery and be charged with attempted murder or murder.  You better be sure that the knife you carry is not a concealed weapon, if you do not have a concealed weapon permit.  This answer does not constitute legal advice nor does it create a lawyer/client relationship. Dr. Michael G. Sribnick, Esq. criminal defense attorney in Charleston, S.C. Michael G. Sribnick, M.D., J.D., LLC