There have been two issues recently which have made me throw the paper onto the floor and shout at the radio in disgust. While it would be great if I could claim that these were issues of great human import – global peace, perhaps, or at least world poverty – they were in fact merely terminological offences, albeit ones that my pedantic nature found deeply disturbing.

The first came over the widespread description of the vote on the 10p tax rate as a possible ‘vote of confidence’. It wasn’t. Had the government been defeated, it would have been hugely, painfully, catastrophically, and probably irretrievably, damaging – but it would not have triggered a visit to the Palace and a general election. That is the consequence of a defeat on a vote of confidence. Anything short of that is merely bluster on the part of the whips, trying to put the willies up the more impressionable backbenchers.

The second came over the widespread certainty among the political class – although not initially the government – that the human fertilisation and embryology bill was an ‘issue of conscience’, on which MPs deserved free votes. Yet the idea that there is such a thing as an ‘issue of conscience’ – one which is divided neatly and precisely from issues not involving conscience – is held only by people who have not thought about the subject for more than, say, 30 seconds. Votes on military action – such as those on Iraq – are routinely whipped, without complaint. MPs must have peculiar consciences indeed if sending troops out to kill or be killed does not affect their consciences, but the hunting of foxes does. If we are willing to whip the former, why not the latter?

The reality is that the definition of what is and is not to be the subject of a free vote is notoriously fuzzy, constantly evolving, and often owes more to calculations of party advantage than to any hard and fast constitutional rules. Capital punishment, for example, was the subject of a whipped vote in both 1948 and 1956 and issues relating to homosexuality and Sunday trading have been both whipped and free over the last couple of decades. Party positions can also differ by party; the Liberal Democrats have occasionally justified whipping gay rights votes on the basis that they saw it as a human rights issue – and why should parties be allowed to opt out of taking a stance on human rights?

It is, however, often sensible politics to grant a free vote, not least because it avoids media coverage of splits and division. Whipping on these issues can also generate resentment among normally loyal MPs, the ‘unusual suspects’, storing up future trouble. That alone – when combined with the presence of cabinet dissenters – made the decision to grant a free vote over the key parts of the human fertilisation and embryology bill justifiable pragmatically.

And anyway, people love it when you have a free vote. When the government allowed a free vote on the issue of smoking in February 2006, the Guardian made ‘free votes’ the subject of its ‘In praise of…’ leader, arguing that they ‘allow MPs to show individual responsibility and to rise above their role as lobby fodder – and that can only be good for parliamentary democracy’.

But it’s not always clear that this is true. In the case of smoking, the free votes resulted in the overturning of part of the election manifesto on which Labour had fought – and won – an election less than a year before. That manifesto was explicit: pubs and bars not serving food ‘will be free to choose whether to allow smoking or to be smoke-free’. When Labour broke its manifesto commitment on university fees during the preceding parliament, there was an outcry; in this case, it got applauded.

Even when they are not on issues that were covered in the manifesto, free votes can be a problem in a system in which voters overwhelmingly vote for parties and not MPs. Free votes allow controversial issues to become detached from the electoral process. However controversial they are, free vote issues vanish from the political radar at election time: manifestos rarely contain more than a passing mention of them (if that); they are largely absent from the national campaign and from media coverage of the election.

This would be problematic enough if they were – as they are usually described – somehow ‘cross-party’ or ‘non-party’. But in reality the party battle lines are almost as entrenched on free votes as they are when the whip is applied – most free votes see the majority of one party in one lobby facing the majority of the other main party in the other lobby – and the outcome of most free votes owes almost everything to the party composition of the Commons. As in both the 1960s and more recently, free votes effectively allow the party in government to enact controversial legislation while simultaneously denying all responsibility for that legislation. It’s not clear to me that this should be celebrated.