Elliot Morley, David Chaytor, Jim Devine and Lord Hanningfield face charges
The Conservative and Lib Dem leaders have urged MPs facing charges over expense claims not to use Parliamentary privilege to avoid court proceedings.
David Cameron said he was "disgusted" by the prospect and Nick Clegg said the public would be outraged.
Lawyers for Labour MPs Elliot Morley, David Chaytor and Jim Devine have all raised the issue of privilege, which usually protects MPs from civil action.
The three MPs all deny charges which they face under the Theft Act.
So does a fourth politician who faces charges - the Tory peer Lord Hanningfield.
The politicians face charges of false accounting under section 17 of the Theft Act 1968. If found guilty they face a maximum sentence of seven years' imprisonment.
In a joint statement, the three Labour MPs, who have been barred from standing as Labour candidates in the general election, said: "We totally refute any charges that we have committed an offence and we will defend our position robustly.
"We maintain that this is an issue that should be resolved by the parliamentary commissioner who is there to enforce any breach of the rules."
Mr Cameron will say more on the issue in a speech on reforming the political system in London on Monday.
It is understood the MPs lawyers might claim their expenses are covered by Parliamentary privilege, which traditionally protects them from being sued for what they say in the Commons.
Announcing the decision to press charges on Friday, the Director of Public Prosecutions Keir Starmer addressed the issue of Parliamentary privilege.
"Lawyers representing those who have been charged have raised with us the question of Parliamentary privilege," he said.
CPS CHARGES LAID
Elliot Morley - two charges over £30,000 of mortgage interest claims
David Chaytor - accused of dishonestly claiming £1,950 for IT services and also £18,000 in rent
Jim Devine - accused of claiming £3,240 for cleaning services and £5,505 for stationery
Lord Hanningfield - faces six charges of dishonestly submitting expense claims
"We have considered that question and concluded that the applicability and extent of any Parliamentary privilege claimed should be tested in court."
Mr Clegg said the public would be "appalled" if the MPs invoked a right going back to 1689. "Lawmakers should not be above the law," he added.
Paul Flynn, Labour MP for Newport West, appealed to his three colleagues to ignore the lawyers' argument about Parliamentary privilege.
He said it was never intended to give politicians "impunity" from criminal charges and if used it would "deepen and prolong" the expenses scandal which had gripped Westminster.
"There may be a technical argument about this but it is one that will be treated with contempt by the majority of the people of the country," he told the BBC.
"Already they feel cynicism about politicians - saying there's one law for MPs and one law for the rest of us."
The Hansard Society, a leading political research and education charity, said any attempts to use parliamentary privilege in these circumstances would be a "deeply damaging" strategy.
Dr Ruth Fox, from the charity, said: "If it is a defence against almost any action that an MP takes in parliament, in any relationship with their work, then I think that is going to be deeply damaging for the public.
"They will see that it is putting MPs above the public, giving them enhanced powers, making them essentially above the laws that they themselves make."
The charges were announced by Mr Starmer following a nine-month police investigation, which was triggered after details of all MPs' expenses claims were leaked to a national newspaper.
Another case remains under investigation but police said in a sixth case - that of Labour peer Lord Clarke - there was "insufficient evidence to provide a realistic prospect of a conviction".
Keir Starmer said defence lawyers had raised parliamentary privilege
The four men will not be arrested but will be sent a summons to turn up on 11 March at City of Westminster magistrates court, a short walk from the Houses of Parliament.
Former minister Elliot Morley, MP for Scunthorpe, faces charges relating to a total of £30,000 of mortgage claims which, it is alleged, were "in excess of that to which he was entitled" and covered a period when there was no mortgage on the property.
David Chaytor, MP for Bury North, is accused of "dishonestly claiming" £1,950 for IT services and further sums of £12, 925 and £5,425 relating to rent on properties which he and his mother allegedly owned.
Livingston MP Jim Devine is accused of "dishonestly claiming" money for cleaning services and for stationery using false invoices.
Paul White - the Conservative peer Lord Hanningfield and leader of Essex County Council - is accused of dishonestly submitting claims "for expenses to which he knew he was not entitled" - including overnight stays in London.
He stepped down as council leader on Friday and as a Tory frontbench spokesman.
He denies the charges and says he will "vigorously" defend himself.
Another fall-out from the expenses scandal was announced on Thursday when 372 MPs were asked to pay back £1.1m as a result of an audit of their claims by Sir Thomas Legg.