Mass. Const. pt. 2, ch. 3, art. 3

In order that the people may not suffer from the long continuance in place of any justice of the peace, who shall fail of discharging the important duties of his office with ability or fidelity, all commissions of justices of the peace shall expire and become void, in the term of seven years from their respective dates; and upon the expiration of any commission, the same may, if necessary, be renewed, or another person appointed, as shall most conduce to the well-being of the commonwealth. [See Amendments, Art. XXXVII.]