Article 1, Section 1
William Blackstone, Commentaries 1:149--51, 156--571765
II. The constituent parts of a parliament are the next objects of our enquiry. And these are, the king's majesty, sitting there in his royal political capacity, and the three estates of the realm; the lords spiritual, the lords temporal, (who sit, together with the king, in one house) and the commons, who sit by themselves in another. And the king and these three estates, together, form the great corporation or body politic of the kingdom, of which the king is said to be caput, principium, et finis. For upon their coming together the king meets them, either in person or by representation; without which there can be no beginning of a parliament; and he also has alone the power of dissolving them.
It is highly necessary for preserving the ballance of the constitution, that the executive power should be a branch, though not the whole, of the legislature. The total union of them, we have seen, would be productive of tyranny; the total disjunction of them for the present, would in the end produce the same effects, by causing that union, against which it seems to provide. The legislature would soon become tyrannical, by making continual encroachments, and gradually assuming to itself the rights of the executive power. Thus the long parliament of Charles the first, while it acted in a constitutional manner, with the royal concurrence, redressed many heavy grievances and established many salutary laws. But when the two houses assumed the power of legislation, in exclusion of the royal authority, they soon after assumed likewise the reins of administration; and, in consequence of these united powers, overturned both church and state, and established a worse oppression than any they pretended to remedy. To hinder therefore any such encroachments, the king is himself a part of the parliament: and, as this is the reason of his being so, very properly therefore the share of legislation, which the constitution has placed in the crown, consists in the power of rejecting, rather than resolving; this being sufficient to answer the end proposed. For we may apply to the royal negative, in this instance, what Cicero observes of the negative of the Roman tribunes, that the crown has not any power of doing wrong, but merely of preventing wrong from being done. The crown cannot begin of itself any alterations in the present established law; but it may approve or disapprove of the alterations suggested and consented to by the two houses. The legislative [Volume 2, Page 25] therefore cannot abridge the executive power of any rights which it now has by law, without it's own consent; since the law must perpetually stand as it now does, unless all the powers will agree to alter it. And herein indeed consists the true excellence of the English government, that all the parts of it form a mutual check upon each other. In the legislature, the people are a check upon the nobility, and the nobility a check upon the people; by the mutual privilege of rejecting what the other has resolved: while the king is a check upon both, which preserves the executive power from encroachments. And this very executive power is again checked, and kept within due bounds by the two houses, through the privilege they have of enquiring into, impeaching, and punishing the conduct (not indeed of the king, which would destroy his constitutional independence; but, which is more beneficial to the public) of his evil and pernicious counsellors. Thus every branch of our civil polity supports and is supported, regulates and is regulated, by the rest; for the two houses naturally drawing in two directions of opposite interest, and the prerogative in another still different from them both, they mutually keep each other from exceeding their proper limits; while the whole is prevented from separation, and artificially connected together by the mixed nature of the crown, which is a part of the legislative, and the sole executive magistrate. Like three distinct powers in mechanics, they jointly impel the machine of government in a direction different from what either, acting by themselves, would have done; but at the same time in a direction partaking of each, and formed out of all; a direction which constitutes the true line of the liberty and happiness of the community.
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The power and jurisdiction of parliament, says Sir Edward Coke, is so transcendent and absolute, that it cannot be confined, either for causes or persons, within any bounds. And of this high court he adds, it may be truly said "si antiquitatem spectes, est vetustissima; si dignitatem, est honoratissima; si juridictionem, est capacissima." It hath sovereign and uncontrolable authority in making, confirming, enlarging, restraining, abrogating, repealing, reviving, and expounding of laws, concerning matters of all possible denominations, ecclesiastical, or temporal, civil, military, maritime, or criminal: this being the place where that absolute despotic power, which must in all governments reside somewhere, is entrusted by the constitution of these kingdoms. All mischiefs and grievances, operations and remedies, that transcend the ordinary course of the laws, are within the reach of this extraordinary tribunal. It can regulate or new model the succession to the crown; as was done in the reign of Henry VIII and William III. It can alter the established religion of the land; as was done in a variety of instances, in the reigns of king Henry VIII and his three children. It can change and create afresh even the constitution of the kingdom and of parliaments themselves; as was done by the act of union, and the several statutes for triennial and septennial elections. It can, in short, do every thing that is not naturally impossible; and therefore some have not scrupled to call it's power, by a figure rather too bold, the omnipotence of parliament. True it is, that what they do, no authority upon earth can undo. So that it is a matter most essential to the liberties of this kingdom, that such members be delegated to this important trust, as are most eminent for their probity, their fortitude, and their knowlege; for it was a known apothegm of the great lord treasurer Burleigh, "that "England could never be ruined but by a parliament:" and, as sir Matthew Hale observes, this being the highest and greatest court, over which none other can have jurisdiction in the kingdom, if by any means a misgovernment should any way fall upon it, the subjects of this kingdom are left without all manner of remedy. To the same purpose the president Montesquieu, though I trust too hastily, presages; that as Rome, Sparta, and Carthage have lost their liberty and perished, so the constitution of England will in time lose it's liberty, will perish: it will perish, whenever the legislative power shall become more corrupt than the executive.
The Founders' Constitution
Volume 2, Article 1, Section 1, Document 2
The University of Chicago Press
Blackstone, William. Commentaries on the Laws of England: A Facsimile of the First Edition of 1765--1769. Chicago: University of Chicago Press, 1979.