Non-disclosure clauses do not protect any employer from illegal acts. If an employee who is covered by the ND provision feels compelled to speak out about what he (or she) believes is illegal conduct, that speech is protected by state and federal whistle blower laws. (Whistle blower lawsuits, by the way, have become a cottage industry for lawyers.) Otherwise, there is no First Amendment issue and the ND restriction is legally binding on the employee. However, as a practical matter, unless the employer suffers financial damages or is defamed it is unlikely to be in the employer's interest to take legal action against the employee as it only invites more publicity, incurs legal fees, and there is very likely little to gain in damages from the employee.