Article 1, Section 6, Clause 1
William Blackstone, Commentaries 1:159--611765
The privileges of parliament are likewise very large and indefinite; which has occasioned an observation, that the principal privilege of parliament consisted in this, that it's privileges were not certainly known to any but the parliament itself. And therefore when in 31 Hen. VI the house of lords propounded a question to the judges touching the privilege of parliament, the chief justice, in the name of his brethren, declared, "that they ought not to make answer to that question; for it hath not been used aforetime that the justices should in any wise determine the privileges of the high court of parliament; for it is so high and mighty in his nature, that it may make law; and that which is law, it may make no law; and the determination and knowledge of that privilege belongs to the lords of parliament, and not to the justices". Privilege of parliament was principally established, in order to protect it's members not only from being molested by their fellow-subjects, but also more especially from being oppressed by the power of the crown. If therefore all the privileges of parliament were once to be set down and ascertained, and no privilege to be allowed but what was so defined and determined, it were easy for the executive power to devise some new case, not within the line of privilege, and under pretence thereof to harass any refractory member and violate the freedom of parliament. The dignity and independence of the two houses are therefore in great measure preserved by keeping their privileges indefinite. Some however of the more notorious privileges of the members of either house are, privilege of speech, of person, of their domestics, and of their lands and goods. As to the first, privilege of speech, it is declared by the statute 1 W. & M. st. 2. c. 2. as one of the liberties of the people, "that the freedom of speech, and debates, and proceedings in parliament, ought not to be impeached or questioned in any court or place out of parliament." And this freedom of speech is particularly demanded of the king in person, by the speaker of the house of commons, at the opening of every new parliament. So likewise are the other privileges, of person, servants, lands and goods; which are immunities as antient as Edward the confessor, in whose laws we find this precept. "Ad synodos venientibus, sive summoniti sint, sive per se quid agendum habuerint, sit summa pax:" and so too, in the old Gothic constitutions, "extenditur haec pax et securitas ad quatuordecim dies, convocato regni senatu." This includes not only privilege from illegal violence, but also from legal arrests, and seisures by process from the courts of law. To assault by violence a member of either house, or his menial servants, is a high contempt of parliament, and there punished with the utmost severity. It has likewise peculiar penalties annexed to it in the courts of law, by the statutes 5 Hen. IV. c. 6. and 11 Hen. VI. c. 11. Neither can any member of either house be arrested and taken into custody, nor served with any process of the courts of law; nor can his menial servants be arrested; nor can any entry be made on his lands; nor can his goods be distrained or seised; without a breach of the privilege of parliament. These privileges however, which derogate from the common law, being only indulged to prevent the member's being diverted from the public business, endure no longer than the session of parliament, save only as to the freedom of his person: which in a peer is for ever sacred and inviolable; and in a commoner for forty days after every prorogation, and forty days before the next appointed meeting; which is now in effect as long as the parliament subsists, it seldom being prorogued for more than fourscore days at a time. But this privilege of person does not hold in crimes of such public malignity as treason, felony, or breach of the peace; or rather perhaps in such crimes for which surety of the peace may be required. As to all other privileges which obstruct the ordinary course of justice, they cease by the statutes 12 W. III. c. 3. and 11 Geo. II. c. 24. immediately after the dissolution or prorogation of the parliament, or adjournment of the houses for above a fortnight; and during these recesses a peer, or member of the house of commons, may be sued like an ordinary subject, and in consequence of such suits may be dispossessed of his lands and goods. In these cases the king has also his prerogative: he may sue for his debts, though not arrest the person of a member, during the sitting of parliament; and by statute 2 & 3 Ann. c. 18. a member may be sued during the sitting of parliament for any misdemesnor or breach of trust in a public office. Likewise, for the benefit of commerce, it is provided by statute 4 Geo. III. c. 33, that any trader, having privilege of parliament, may be served with legal process for any just debt, (to the amount of 100l.) and unless he makes satisfaction within two months, it shall be deemed an act of bankruptcy; and that commissions of bankrupt may be issued against such privileged traders, in like manner as against any other.
The Founders' Constitution
Volume 2, Article 1, Section 6, Clause 1, Document 3
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.
Easy to print version.