The Crown Prosecution Service is to announce whether it will bring charges against another politician over the expenses scandal.

Three Labour MPs and a Conservative peer on Thursday told a judge they will use a 320-year-old law to argue they should not be prosecuted.

MPs David Chaytor, Elliot Morley and Jim Devine, along with Lord Hanningfield, will insist their case should not be tried by a jury and instead dealt with by House of Commons authorities.

The four were charged last month. The CPS announced there was insufficient evidence to bring charges against a fifth politician, Labour peer Lord Clarke of Hampstead.

In an unprecedented hearing at City of Westminster Magistrates' Court on Thursday, all four Parliamentarians said they would plead not guilty to fiddling claims for allowances.

District Judge Timothy Workman agreed the case was so serious it should be heard at a higher court and released the four defendants on unconditional bail to appear at Southwark Crown Court on March 30. If convicted, they face a maximum sentence of seven years in prison.

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.

Scunthorpe MP Morley, 57, of Winterton, North Lincolnshire, allegedly falsely claimed £30,428 in interest payments between 2004 and 2007 towards a mortgage on his home he had already paid off.

Livingston MP Devine, 56, of Bathgate, West Lothian, is said to have wrongly submitted two invoices worth a total of £5,505 for services provided by Armstrong Printing Limited. He also faces a second charge alleging he dishonestly claimed cleaning and maintenance costs of £3,240 by submitting false invoices from Tom O'Donnell Hygiene and Cleaning Services.

Hanningfield, also known as Paul White, 69, of West Hanningfield, near Chelmsford, Essex, faced six charges of making dishonest claims for travelling allowances. Each charge claimed the former leader of Essex County Council "purported to show that you were entitled to be paid expenses when the conditions entitling you to payment of such expenses had not been fulfilled".