Milosevic, Hussein, Charles I, and many others have refused to recognise the jurisdiction of the various courts that tried them. Charles I found his refusal to enter a plea taken pro confesso, i.e. as a guilty plea. He was executed, and that was the end, for a short while, of the idea that rex WAS lex. Still, Charles II sorted out those uppity lawyers, mainly by killing them in a variety of horrible ways.
Geoffroy Robertson QC has written many books dealing with war crimes, all of which deal with the refusal by a toppled leader to recognise the jurisdiction of the court to try him.
The Bill of Rights holds that "proceedings in Parliament" shall not be discussed before a court. The three members of the lower House, and the one peer to have been charged in what has become known simply as "The Expenses Scandal", are all backing the same horse. They will argue (and the issue will no doubt be decided as a preliminary issue at the beginning of the trial proper) that their claims for expenses to which they may or may not have been entitled were "proceedings in Parliament", and that the principle of the separation of powers should not be infringed, and the judiciary should not interfere with the legislature.
MPs are free to make all sorts of slanderous statements on the floor of the House, their freedom of speech is well-protected, and rightly so. Where, though, is the line to be drawn? Is the separation of powers a constitutional principle to which the judiciary are so highly attached that they will cast the defendants upon the (apparently abundant) grace of their internal disciplinary proceedings?
I would tentatively suggest that the highest courts in the land will be asked to rule on this issue only when we are well into the next parliament, however that may be constituted. Much ink will no doubt be spilt. All I will say at this very early juncture is this; claiming many hundreds of pounds a month in interest repayments on a mortgage that was long-since paid off is clumsy at best and criminal at worst. It certainly won't win you many votes.
I will also add that my cockles were well and truly warmed when I heard that the application for the men to remain in the well of court was given the short shrift it deserved. Such applications rarely succeed, unless the defendant is in a wheelchair, deaf, or has some other inherent incompatibility with being in the dock. The Right Honorable (sic) gentlemen had no such difficulties, as far as I am aware.
Given the publicity that will inevitably attach to the first appearance by members of parliament before the criminal courts since the 17th century, it seems that they and their lawyers failed properly to consider the public relations ramifications of such an application.