Mass. Gen. Laws ch. 231, § 67: Non-disclosure of information not pertinent

Section 67. Sections sixty-one to sixty-six, inclusive, shall not affect the right of a party interrogated, under the direction of the court, to seal up or otherwise protect from examination such parts of any document, book, voucher or other writing as contain matters not pertinent to the subject of the action, or affect the power of the court to protect said right, or any right of the party interrogated, by suitable order.