We can't allow the government to introduce legislation which allows the ID card database to be used for tax enforcement

Campaigners against ID cards have warned for years that the ID verification process will give the authorities power to monitor a person's spending and draw conclusions about their tax declarations and real income.

These fears were dismissed by government supporters and journalists as hysterical but now they turn out to be rather well-founded.

Secondary legislation laid before parliament last week reveals that the taxman will have access to the log of a person's major transactions, hotel bookings, airline tickets, holidays, car payment plans etc. Naturally the subject of this inspection will have no idea that HM Revenue and Customs is examining their spending log or what deductions, false or otherwise, will be made.

As the Daily Mail pointed out this legislation was quietly introduced to parliament at the very moment that MPs' fraudulent and tax-avoiding affairs were being revealed by the Daily Telegraph. A piquant detail in the long story of how parliament has come to revile the ordinary member of the public.

It is absolutely essential for civil society and the conduct of our democracy – or what remains of it – that faceless bureaucrats are not given the power to look into individuals' spending. It is another line drawn in the sand that we allow the executive to cross at our peril. I suggest that we should regard it as part of the battle to equalise the power of the government and the people.

But there are many who do not see the threat and indeed argue for even greater intrusion and data collection by the state. David Goodhart, the editor of Prospect magazine, wrote recently: "If there is too much suspicion of the state and too many data protection rules the state cannot give us what we want. It might be useful if we started to see out data as similar to tax, something we willingly surrender to the authorities in return for various benefits."

In this newly announced piece of legislation, tax and data become intimately associated in a way that Goodhart no doubt applauds. But it never seems to occur to critics that the state has no natural right to either tax or information. Both are given up only with our consent, which depends on the demonstrable competence and propriety of the state, something that none of us could swear to today.

Goodhart's is the argument of tyrants and slaves, it urges us to trust the state regardless of the evidence of its fallibility. Incidentally, it seems ironic that this statist line appears in a magazine part–owned by two wealthy financiers, one of whom, George Robinson is a hedge fund manager who made £18m in 2004 on a turnover of £74m, income that no doubt benefited from the favourable tax environment devised for hedge funds by Gordon Brown.

The supporters of state databases are going to have to campaign very hard over the coming months, not just about intrusion, but also data security. It will be interesting to see how they propose to guarantee the safety of our data after the 11th day of revelations by the Daily Telegraph, which of course all come from a breach of an official database, just like the one that will monitor our spending.