In another question's comments is claimed that the right for aristocratic peers to be tried by their own kind had ended in 1948. How and why did it end then?
The privilege of peerage in criminal proceedings was abolished by s. 30 of the Criminal Justice Act 1948.
As for why, see Colin Rhys Lovell, "The Trial of Peers in Great Britain", The American Historical Review, Vol. 55, No. 1 (Oct., 1949). There were "grave disadvantages in the procedure to the accused peer, who could not waive it." The accused could not challenge the jurors or appeal their decisions. It was ultimately decided that the procedure had "outlived its usefulness."
See also some justification from Hansard:
[...a peer] cannot say, "Waive all this, and treat me like anybody else." The existing law is that he must be tried by this grotesque and antiquated arrangement. It is a Court, but it is a very ancient Court, and it is high time that provisions were made that a Peer who is charged with a felony should be treated in the same way as anybody else.
From the Hansard reference given above:
I hope that before this Bill is presented for the Royal Assent it may include a clause which will get rid, once and for all, of what I regard as a preposterous anachronism which attaches to your Lordships' House. The House is no doubt aware that if a Peer of the Realm is charged with committing a felony, he has, at the present time, to be tried in a special court called the Court of the Lord High Steward, assembled, I suppose, in existing circumstances, in the corridor outside—certainly there would be no room for it here. On the last occasion when it assembled, not so very long ago, in 1936, it was attended by 200 to 300 peers, all wearing their robes. It consists, if I may say so with respect to your Lordships' House, of a mob of persons, presided over by the Lord Chancellor under a special Commission, carrying a white wand, which he solemnly breaks across his knee at the end of the proceedings to show that the Court is for the time being discharged. The Peer has to face this unpleasant experience. He may be innocent, but he cannot say, "Waive all this, and treat me like anybody else." The existing law is that he must be tried by this grotesque and antiquated arrangement. It is a Court, but it is a very ancient Court, and it is high time that provisions were made that a Peer who is charged with a felony should Toggle showing location ofColumn 404be treated in the same way as anybody else.
In case any noble Lords should be contemplating a breach of the criminal law (which I do not for a moment assume), I would like to point out for your Lordships' information that it would be very useful to learn accurately the difference between a misdemeanour and a felony. If it is a misdemeanour, you go to the Old Bailey and stand in the dock like anybody else. Obtaining money by false pretences is a misdemeanour. Stealing, however, is a felony. The line between those two is sometimes difficult to draw. Take the best legal advice before you commit yourselves to an undesirable form of crime! But there are other absurdities quite as ridiculous. According to the books the rule does not apply to an Irish Peer who is a Member of the House of Commons. To other Irish Peers who are Members of your Lordships' House it does apply. To put it in a more personal form—although each case I take is, of course, the very wildest hypothesis—if Lord Winterton were to commit a felony, he would go to the Central Criminal Court, but if the Lord Chairman of Committees, the Earl of Drogheda, equally improbably, were to be "caught out" in such a case, he would appear before the Court of the Lord High Steward. And still more extraordinary! I see opposite me the Bench of Bishops, and perhaps I may be allowed to mention this, as possibly it will be a piece of information: the Spiritual Peers of this House are not regarded in law as noble by blood. The consequence is that, in the inconceivable case of any member of that Order committing a crime, either felony or misdemeanour, and I will add, being found out, he would be tried just like any common man.
On the other hand, however—and this is most extraordinary—it is a tradition and right of the Spiritual Peers to attend in this crowd of persons drawn from this House to try a Peer, but with this refinement: that while they attend and take part, they ask leave to withdraw before sentence is pronounced. Is it not high time that we took advantage of this Bill and got rid of all that? If I am able to carry out my present purpose I shall, on my own account—it is not a matter on which I have been able to consult my fellows—put down as a new clause an Toggle showing location ofColumn 405Amendment to that effect, and I hope it may receive special consideration from the noble and learned Viscount the Lord Chancellor.