The fact that MPs are lawmakers doesn’t license them as lawbreakers. So it’s reassuring that the High Court has just ruled against Parliament’s attempt to stop the full disclosure of MPs' second-home expenses.

At the heart of the case is this question: should MPs be able to spend taxpayers’ hard-earned money on themselves without saying how they spend it?

Since 1971, MPs who represent constituencies outside London have been allowed to claim expenses for property to live in while they’re on Parliamentary business. This is called an Additional Costs Allowance (ACA). The recent case Corporate Officer of the House of Commons v The Information Commissioner arose because some members of the public tried to use the Freedom of Information Act 2000 to get details of the expenditure of 14 MPs but were rebuffed. The Information Tribunal (which adjudicates on freedom of information issues) then ruled that the financial details should be made public. The High Court has just backed that decision.

The 14 MPs (including Gordon Brown, David Cameron, George Osborne, Margaret Beckett and Mark Oaten) did not personally get involved in the litigation; the case against them disclosing expenditure details of their substantial allowances was championed by a House of Commons official.

The dispute centres on the core principles of two pieces of legislation. These are the Freedom of Information Act 2000, which gives the democratic right to information held by public authorities, and the Data Protection Act 1998 which protects sensitive personal data. An MP is clearly entitled to privacy on matters such as their health records. But can they say that how they spend large sums of money — such as £40,000 — from the public purse is a private matter?

In modern Britain, the state comes down hard on anyone who misuses money from the public purse. If you improperly claim £400 from the state you will be in a lot of legal trouble. What about if you claim £40,000? Sir Igor Judge, President of the Queen’s Bench Division of the High Court, noted that there was evidence which suggested that one MP claimed an allowance for “a property which did not exist”, and further evidence that could suggest MPs were claiming allowances but letting out the accommodation procured from the allowance.

Sir Igor Judge said: “We are not here dealing with idle gossip, or public curiosity about what in truth are trivialities.” He ruled that the expenditure of public money through the payment of MPs' salaries and allowances “is a matter of direct and reasonable interest to taxpayers”. Gravely and aptly, the judge noted that the rules about MPs allowances “bear on public confidence in the operation of our democratic system at its very pinnacle, the House of Commons itself.”

So, what were the arguments put forward by the Corporate Officer of the House of Commons (the Officer) to resist the full disclosure of MPs expenditure? You’ll be shocked. The truth is that if these arguments were stripped of legal language and recounted in ordinary phrases over a pub table they’d be seen as comically weak.

It was argued, for example, that details of the expenses shouldn’t be exposed because there would be a fuss in the media and that would distract MPs from their work. Don’t bother me with awkward questions about possible wrongdoing, I’m a busy politician.

It was also argued that requiring the publication of the expenses “would be liable to discourage the most able citizens from seeking election to the House”. Why honest citizens would be deterred from standing as MPs just because their housing expenses could be made public wasn’t explained by lawyers for the Commons.

But the oddest reason why it was suggested that disclosure of MPs housing expenses would be unfair was that to do so would contradict “the reasonable expectations of MPs”. That argument boiled down to saying “we didn’t realise when we applied for these huge sums for housing that we’d ever be expected to disclose the full details”.

In other words, they didn’t know how the Freedom of Information Act 2000 works. But how could they not know — the very job for which they were claiming such huge expenses was that of legislator. The Freedom of Information Act is their creation. It was made in their House. They work in the law factory, the House of Commons, and they more than anyone else must be expected to know their own products.

This isn’t a story of judges interfering with the supremacy of Parliament. There is a law to prevent that: the Bill of Rights 1689. That was passed to stop royal power trying to control and intimidate Parliament, and it says that proceedings in Parliament “ought not to be impeached or questioned in any Court”. But all that the High Court did last week was rule that once an Act has been passed, MPs can’t exempt themselves from it. They must comply with the Freedom of Information Act however embarrassing that is for them.

If it turns out that the MPs who’ve been hammering chavs for making improper benefits claims have themselves been making less than perfect claims on their own state benefits then they’ll have to be judged by that court of ultimate power: the electorate.

Professor Slapper is Director of the Centre for Law at The Open University

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