Home Secretary Alan Johnson has flatly rejected the idea that MPs accused of fiddling their expenses should be able to use parliamentary privilege as a "get out of jail card".
Mr Johnson insisted it was vital that the three Labour MPs and one Tory peer charged with false accounting should be treated exactly the same as any other members of the public.
The intervention came amid speculation that Elliot Morley, David Chaytor and Jim Devine will argue that the principle of parliamentary privilege exempts them from prosecution.
It has also emerged that the trio are likely to receive tens of thousands of pounds in 'golden goodbyes' when they stand down from the Commons. Legal advisers to Speaker John Bercow are understood to be examining whether the resettlement grants can be withheld or delayed while the court process is completed.
However, they have yet to find a way that satisfies "natural justice" as the men have not been convicted of any crime.
The MPs and Lord Hanningfield deny the charges, and have pledged to defend themselves "robustly".
Members who leave parliament at a general election are entitled to pay-offs of up to £65,000 each, depending on their age and service.
Interviewed on the BBC's Andrew Marr show, Mr Johnson insisted the 1689 Bill of Rights - which enshrined the principle of parliamentary privilege - was not meant to deal with "this kind of issue".
"My colleagues in parliament should get a fair trial," he said. "That fair trial should be on the same basis as any member of the public who goes through the courts system. The whole point about this, this dreadful, dreadful, damaging year that we have had here, is that people want to see MPs treated in the same way as they would be treated had they broken the law."
Mr Johnson went on: "A few, a very few, have been thought to have broken the law. That is the accusation. They are entitled to a fair trial. I think the public would be aghast if they thought there was some special get out of jail card for parliamentarians."