"when the legislative and executive powers are united in the same person, or in the same body of magistrates, there can be no liberty; because apprehensions may arise, lest the same monarch or senate should enact tyrannical laws, to execute them in a tyrannical manner.

again, there is no liberty, if the judiciary power be not separated from the legislative and executive. were it joined with the legislative, the life and liberty of the subject would be exposed to arbitrary control; for the judge would be then the legislator. were it joined to the executive power, the judge might behave with violence and oppression."
the quotation above is a translation from french philosopher montesquieu’s the spirit of the laws. which constitutional principle of the founding fathers is expressed in this passage?