Massachusetts Constitution Pt. 1, Art. 29

ART. XXIX. It is essential to the preservation of the rights of every individual, his life, liberty, property, and character, that there be an impartial interpretation of the laws, and administration of justice. It is the right of every citizen to be tried by judges as free, impartial and independent as the lot of humanity will admit. It is, therefore, not only the best policy, but for the security of the rights of the people, and of every citizen, that the judges of the supreme judicial court should hold their offices as long as they behave themselves well; and that they should have honorable salaries ascertained and established by standing laws.