The furore over MPs' expenses in recent days spilled onto our website today when we ran the story about Keith Vaz's £80,000 claims for the past four years.

The article probably attracted more comment than any other in recent months ... but they weren't all printable! We use a system of post-moderation on our site: that is we allow people to comment directly on to the site and then we go on afterwards and check them for decency and libel issues. This means that we quite often end up removing comments a little while after they have appeared and this in itself often leads to our readers complaining that their comments have been taken down. Usually they accuse us of censorship.

In fact, we usually remove comments either because they are not appropriate - they might be racist, or full of personal abuse, for example - or because they leave us open to being sued for defamation.

It's quite easy to confuse a statement of opinion, which can't really be said to be libellous, and a statement of fact, dressed up as opinion, which may well be defamatory. Let's, for a moment, consider an imaginary MP. It is quite acceptable to say that you think it is disgraceful that this MP has claimed expenses and that you feel he should be sacked from the Government and that voters should refuse to re-elect him at the next general election. You can go on to say that you think he is an idiot who has shown a complete lack of common sense. However, it would almost certainly by libellous to say that an MP was on the fiddle or that you always knew he was corrupt and open to bribery - that is to say, it would be libellous unless you could prove that it was true.

There's no doubt that there is a great deal of anger out there over the claims made by MPs and we are happy to reflect this - we've said in our own leader articles what we think - but the arguments for reform remain much stronger if we don't allow our comments to sink into personal abuse or allow the MPs to deflect the criticism by suing the newspaper over errors of fact.