Three former Labour MPs and a Tory peer today lost appeals over a ruling that they are not protected from prosecution by parliamentary privilege over allegations that they fiddled their expenses.
Court of Appeal judges in London rejected challenges brought by David Chaytor, Elliot Morley, Jim Devine and Lord Hanningfield, who deny theft by false accounting.
The four appealed against a ruling in June by Mr Justice Saunders, sitting at Southwark Crown Court in central London.
He rejected arguments that they were protected by parliamentary privilege and should be dealt with by Parliament alone.
Today, the Lord Chief Justice, Lord Judge, sitting with Lord Neuberger and Sir Anthony May, agreed with the judge.
Each of the four defendants, who are all on unconditional bail, face separate criminal trials as a result of the ruling.
But it is open to them to seek to take their case to the Supreme Court for a further challenge.
Former Bury North MP Chaytor, 60, of Todmorden, Lancashire, is accused of falsely claiming rent on a London flat he owned, falsely filing invoices for IT work and renting a property from his mother, against regulations.
Ex-Scunthorpe MP Morley, 58, of Winterton, North Lincolnshire, is charged with falsely claiming £30,428 in interest payments between 2004 and 2007 towards a mortgage on his home which he had already paid off.
Devine, 57, of Bathgate, West Lothian, formerly MP for Livingston, is accused of wrongly submitting two invoices worth a total of £5,505 for services provided by Armstrong Printing Limited.
He also faces a second charge alleging that he dishonestly claimed cleaning and maintenance costs of £3,240 by submitting false invoices from Tom O'Donnell Hygiene and Cleaning Services.
And former Essex County Council leader Lord Hanningfield, who is also known as Paul White, 69, of West Hanningfield, near Chelmsford, Essex, faces six charges of making dishonest claims for travelling allowances.
Giving the judgment of the court, Lord Judge said: "It can confidently be stated that parliamentary privilege or immunity from criminal prosecution has never, ever attached to ordinary criminal activities by Members of Parliament.
"With the necessary exception in relation to the exercise of freedom of speech, it is difficult to envisage circumstances in which the performance of the core responsibilities of a Member of Parliament might require or permit him or her to commit crime, or in which the commission of crime could form part of the proceedings in the House for the purposes of Article 9 of the Bill of Rights."
He added: "Equally, we cannot discern from principle or authority that privilege or immunity in relation to such conduct may arise merely because the allegations are based on activities which have taken place 'within the walls' of Parliament."
The judge said: "The stark reality is that the defendants are alleged to have taken advantage of the allowances scheme designed to enable them to perform their important public duties as Members of Parliament to commit crimes of dishonesty to which parliamentary immunity or privilege does not, has never, and, we believe, never would attach.
"If the allegations are proved, and we emphasise, if they are proved, then those against whom they are proved will have committed ordinary crimes.
"Even stretching language to its limits, we are unable to envisage how dishonest claims by Members of Parliament for their expenses or allowances begin to involve the legislative or core functions of the relevant House, or the proper performance of their important public duties.
"In our judgment, no question of privilege arises, and the ordinary process of the criminal justice system should take its normal course, unaffected by any groundless anxiety that they might constitute an infringement of the principles of parliamentary privilege."
He concluded that the decision of Mr Justice Saunders was "correct", announcing: "The appeals will be dismissed."
Lord Judge said: "The issue of parliamentary expenses, the arrangements by which they are claimed, and in some cases the amounts claimed and the items for which claims were made, has excited huge public interest and, certainly on occasions, profound concern.
"Inevitably, the closest attention has focused on those members who have been prosecuted in connection with their claims.
"Just because of the publicity which the cases have attracted, it remains to be emphasised that none has been convicted, each is presumed to be innocent, and the evidence in support of the allegations made against them has not yet been tested, evaluated and judged by a jury."
The appeals raised "important questions of public interest about the nature and ambit of parliamentary privilege" and had required examination in depth.