Colin Challen: If parties lie or dissemble, they must pay the penalty for deceiving voters

I'm all in favour of scrapping the first past the post (FPTP) system of electing MPs – over the lifespan of the Parliamentary Labour Party it has done us few favours. After Labour came to power in 1997, we gradually whittled away at FPTP in the elections for Europe and the devolved administrations. If we had direct elections to a second chamber to replace the Lords it would now be inconceivable to use FPTP.

But the debate on alternative voting is superficial. It sidesteps important issues which it seems are too close to the democratic bone to be dissected in public. The most pressing issue has to be about political accountability, chiefly in circumstances when a coalition government is elected (as seems more likely these days) but even when one party achieves power on its own.

Political accountability means "doing what you promised". Yes, I mean actually doing it. Delivering on those promises that were made at election time. Indeed, political accountability means being honest about all policies, both your own and your critique of others'. If we are to have a greater prospect of coalition government, then we cannot afford to have a replication of the manner in which the present Conservatives and Liberal Democrats came to power this year.

When the Yorkshire Post reproduced the photograph of Nick Clegg standing in front of his party's attack poster on the Conservative's presumed fondness for raising VAT, it reminded us of one of the cynical ploys political parties get up to in elections. Vince Cable has since described this as simply election point scoring, undermining his own reputation as an honest politician.

The fact is, by highlighting so publicly and negatively a policy ascribed to an opponent, the public could only be allowed one conclusion: the Lib Dems themselves opposed a VAT rise. Cable went on to say: "Well, that was the General Election, we've moved on".

Frankly Dr Cable, it shouldn't be that easy. But for now I'll leave this particular episode, and no doubt plenty of other possible let downs, to Liberal Democrat party members to chew over. What I want to suggest is that the very nature of coalition government will need addressing if we are to have an electoral system which makes coalitions more likely. Since I am not against the possibility of coalitions, I want to see them work. But above all we – the electorate – should be confident about what it is we're voting for. We cannot have parties using coalition-forming processes simply to chuck overboard key election pledges they made in order to gain power.

As a first step (and there are others) I'm calling for a Political Standards Authority (PSA) to do for political parties what trades descriptions legislation does for dodgy traders. If a party says it will do something then it should be held to it. If it finds it cannot deliver, it has to be forced to say why. If parties want to lie, obfuscate, change their minds or dissemble, then let them face the penalty for deceiving voters, with sanctions up to and including outright bans on future participation in elections, hefty fines on leaders and suspension from Parliament.

Most of the reforms that parties are generally prepared to accept do not address the fundamental question of simply telling the truth. It is almost second nature for politicians to be economical with the actualiti for a large variety of reasons, some of them even justifiable. But if we are to avoid engendering even more cynicism among the public, we ought to install some safeguards against political cynicism among the practitioners.

The PSA would comprise expert and knowledgeable people, whose service would preclude them from being active in party politics 10 years either side of their membership of it (that lets me out then). They would have the power to receive complaints from any source, and very much like the Parliamentary Ombudsman, would make judgments on those complaints it deemed serious enough and based on enough evidence to pursue. Its judgments should have the force of law. Transgressors should face the penalties I mentioned above.

What is the difference between somebody who sells you a pig in a poke and an undeclared fiscal policy? Why should one face criminal prosecution and the other merely a sweaty moment on the floor of the Commons? For millions of people, the policies (or absence of

them) offered in general elections are real and substantive things, not merely the latest outpouring of an adolescent think tank. Real jobs, real schools, real issues – when you only have one chance every five years to make this "purchase" you should get what it says on the can.

We live in a consumer age, and our politics reflect consumerist behaviour with behind-the-scenes political marketing easing out old fashioned ideas about ideology and replacing it with up-to-the-minute branding. We need new controls to ensure that this quiet revolution does not eviscerate the voter's contract with the politician.

Colin Challen was the Labour MP for Morley and Rothwell from 2001 to 2010