The members’ tea room in the House of Commons has been buzzing this week in a way that I have not seen for some time.

What, I hear you ask, has stirred up our nation’s legislators in this way? You might think it would be spending cuts or maybe the closure of RAF bases or maybe even changes to benefit rules. No. The thing that seems to have animated parliament this week is the decision of an election court at the end of last week that Labour MP Phil Woolas ran such a dishonest campaign in the May election that he was guilty of illegal practice under the Representation of The People Act 1983.

The election result was void and that there will have to be a by-election. Mr Woolas had distributed leaflets during the campaign stating that his Liberal Democrat opponent sought to woo the support of Islamic fundamentalists who supported the use of violence. It was brutal stuff.

We have had some vigorous debates in the isles over the years but by and large they have focused on the issues and not been personal­ised. It is a political tradition that we should be careful to preserve.

It is, I am told, the first time in 99 years that a court has returned a ver­dict of this sort. That in itself should give you some idea of how extrava­gant (and damaging) some of the claims made by Mr Woolas were.

The buzz in the tearoom, how­ever, is that this judgment is an unjusti­fiable interference in the political process by the courts. A politician, the argument seems to go, should be allowed to make whatever outrageous and untruthful claim that he or she wants about an opponent.

It is a thoroughly depressing argu­­ment to listen to. Everyone knows that politics is a robust trade, especially in an election campaign. No-one would expect candi­dates to spend their time highlighting their opponents’ virtues but to suggest any smear is justifiable must be wrong.

Most worryingly it betrays an attitude that I had hoped would have been eradicated by the expenses scandals of the last parliament – namely that different rules should apply to MPs than apply to the rest of the population. If Tesco tried to smear the Co-op in the same way it would soon be in trouble. Why should politics be different?

Harriet Harman must be wonder­ing when she will next be able to open her mouth without upsetting someone. A couple of weeks ago she had to apologise for referring to my colleague Danny Alexander as a “ginger rodent”. She might have thought she was on safer ground dis­owning Mr Woolas and his activities, but no. She has been faced by what is described by insiders as a “mutin­ous reaction” by Labour MPs. There is talk of them all chipping in to a fighting fund to help pay for their former colleague’s legal fees.

The right to freedom of speech is a fundamental one but it does bring a responsibility with it to tell the truth. The right to smear an opponent is not one we should be defending.

Alistair Carmichael MP