The Equal Employment Opportunity Commission has taken a position similar to the National Labor Relations Board. The EEOC notified an employer that it considers enforced secrecy during internal harassment investigations to be unlawful. The NLRB similarly discourages an instruction to maintain confidentiality, finding that it tramples on employees’ rights to discuss their terms and conditions of employment. The EEOC similarly fears that an instruction not to speak about incidents of harassment or discrimination may stop an employee from filing charges of discrimination.
Both agencies recognize that the integrity of the investigation is an important factor, and therefore in certain circumstances the employer may caution the employees to maintain confidentiality over certain facts. It’s the blanket prohibition that violates the spirit of the employee protection laws.