Article 1, Section 6, Clause 1
Thomas Jefferson (AND James Madison), Protest to the Virginia House of Delegates1797Works 8:322--23, 325--27
That in order to give to the will of the people the influence it ought to have, and the information which may enable them to exercise it usefully, it was a part of the common law, adopted as the law of this land, that their representatives, in the discharge of their functions, should be free from the cognizance or coercion of the co-ordinate branches, Judiciary and Executive; and that their communications with their constituents should of right, as of duty also, be free, full, and unawed by any: that so necessary has this intercourse been deemed in the country from which they derive principally their descent and laws, that the correspondence between the representative and constituent is privileged there to pass free of expense through the channel of the public post, and that the proceedings of the legislature have been known to be arrested and suspended at times until the Representatives could go home to their several counties and confer with their constituents.
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That when circumstances required that the ancient confederation of this with the sister States, for the government of their common concerns, should be improved into a more regular and effective form of general government, the same representative principle was preserved in the new legislature, one branch of which was to be chosen directly by the citizens of each State, and the laws and principles remained unaltered which privileged the representative functions, whether to be exercised in the State or General Government, against the cognizance and notice of the co-ordinate branches, Executive and Judiciary; and for its safe and convenient exercise, the intercommunication of the representative and constituent has been sanctioned and provided for through the channel of the public post, at the public expense.
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That the grand jury is a part of the Judiciary, not permanent indeed, but in office, pro hac vice and responsible as other judges are for their actings and doings while in office: that for the Judiciary to interpose in the legislative department between the constituent and his representative, to control them in the exercise of their functions or duties towards each other, to overawe the free correspondence which exists and ought to exist between them, to dictate what communications may pass between them, and to punish all others, to put the representative into jeopardy of criminal prosecution, of vexation, expense, and punishment before the Judiciary, if his communications, public or private, do not exactly square with their ideas of fact or right, or with their designs of wrong, is to put the legislative department under the feet of the Judiciary, is to leave us, indeed, the shadow, but to take away the substance of representation, which requires essentially that the representative be as free as his constituents would be, that the same interchange of sentiment be lawful between him and them as would be lawful among themselves were they in the personal transaction of their own business; is to do away the influence of the people over the proceedings of their representatives by excluding from their knowledge, by the terror of punishment, all but such information or misinformation as may suit their own views; and is the more vitally dangerous when it is considered that grand jurors are selected by officers nominated and holding their places at the will of the Executive . . .; and finally, is to give to the Judiciary, and through them to the Executive, a complete preponderance over the legislature rendering ineffectual that wise and cautious distribution of powers made by the constitution between the three branches, and subordinating to the other two that branch which most immediately depends on the people themselves, and is responsible to them at short periods.
The Founders' Constitution
Volume 2, Article 1, Section 6, Clause 1, Document 18
The University of Chicago Press
The Works of Thomas Jefferson. Collected and edited by Paul Leicester Ford. Federal Edition. 12 vols. New York and London: G. P. Putnam's Sons, 1904--5.
Easy to print version.