From James Madison, Federalist 10
No man is allowed to be a judge in his own cause because his interest would certainly bias his judgment, and, not improbably, corrupt his integrity. With equal, nay with greater reason, a body of men are unfit to be both judges and parties at the same time; yet what are many of the most important acts of legislation but so many judicial determinations, not indeed concerning the rights of single persons, but concerning the rights of large bodies of citizens?
And a quote from George Washington.
Legislatures, through a long succession of years, are laid open for our use, and their collected wisdom may be happily applied in the Establishment of our forms of Government; the free cultivation of Letters, the unbounded extension of Commerce, the progressive refinement of Manners, the growing liberality of sentiment, and above all, the pure and benign light of Revelation, have had a meliorating influence on mankind and increased the blessings of Society. At this auspicious period,
Circular Letter to the States
the United States came into existence as a Nation, and if their Citizens should not be completely free and happy, the fault will be entirely their own.
George Washington, "Circular to the States," June 8, 1783, in W.W. Abbot et al., eds., The Papers of George Washington, 1748–1799