If you Google, try googling (in the UK entries section) the following assemblage of words and phrases: “this bill”, “send out”, “message”, “minister” and “Parliament”. I got 676 returns yesterday.

How often have we read or heard it? New laws and proposed new laws are being touted around as though they were a specialised branch of advertising, rather than rules to be interpreted, enforced and obeyed. MPs become briefly enthused as the legislation passes through their House - and then, once passed and even before it comes into force, seem to lose interest in whether the law is working. It is as though they think that, message sent, their work is done. Ask almost any MP whether he or she has the least idea how many prosecutions have so far been brought under an Act that not many months ago they were touting as a vital part of the Government's programme (or the beginning of the end of civilisation as we know it) - and they won't have a clue. They have moved on in their minds to new messages they want to send out.

A Private Member's Bill that got its second reading in the House of Commons yesterday was most certainly not intended as merely declaratory. But it was there to amend an area of law that for 1.4 million people has indeed become no more than an exhortation: employment protection. There are now 1.4 million agency workers in Britain and the sector is expanding, driving a coach and horses through our employment protection laws. The Temporary and Agency Workers (Equal Treatment) Bill, sponsored by the Labour backbencher Andrew Miller, would give agency workers parity with those on permanent company payrolls by whose side they often work, doing just the same jobs.

My own mind tends to a different conclusion from Mr Miller's: that there should indeed be better parity between the agency worker and his company-payrolled equivalent; but this should be achieved not by increasing the rights of the former, but reducing the rights of the latter. But that's another argument. Where Mr Miller's logic and mine agree is in this: that ministers seem happy to trumpet Britain's employment protection legislation as an example of social justice in action, while allowing agency working to undermine its whole purpose - perhaps aware that the added flexibility in the labour market is an economic good that they dare not tamper with.

We in Britain are getting into a dreadful habit. I call it “declaratory” lawmaking. I mean making laws that do not so much do the right thing, as say the right thing. Content with the “message” our new Act of Parliament has “sent out”, we then start working assiduously to subvert the natural consequences of enforcing it.

If we think that workers' rights enshrined in European and British law are necessary safeguards against exploitation, then Mr Miller is right: we should stop up the expanding loophole of agency working. If we don't, we should never have enacted the legislation in the first place.

Such moral and intellectual dishonesty seeps through modern attitudes to lawmaking. Take the 2000 Act reforming party funding. No sooner had it received Royal Assent - and “sent out a signal” that the years of Tory sleaze were over - than Tony Blair's political comrades began undermining it by resorting to loans instead of donations. They're doing so still.

Or take the anti-corruption laws enacted in the Crime and Security Act (2001) during that same spate of (apparently) reforming zeal. Ministers and civil servants never for a moment supposed that their new law need impede the kickback-littered progress of Britain's arms-trading relationship with Saudi Arabia - and secretly blocked a Serious Fraud Office inquiry when it did.

Or take a more ancient (and seminal) piece of lawmaking: Britain's accession to the 1951 Geneva Convention on Refugees. The world has changed since. Almost the entire female population of Saudi Arabia (for example) could arguably avail themselves of the sanctuary that this measure offers; and mass international transport gets ever easier. But, lacking the philosophical courage to admit that the convention needs amending, we and our allies have constructed walls not so much of red tape as barbed red wire: interminable delays, fines on airlines, miserly welfare, armed patrols off the African coast beating back pathetic rowing-boats... all in an attempt to make it prohibitively difficult for the would-be refugee to reach the position in which he could make the claim. This is cowardly.

More ancient still is our National Health Service and its bedrock principle of unlimited care free to all at the point of use. Who dares revisit that bedrock? Nobody. So instead we charge for prescriptions, not care; we run down NHS dentistry until you cannot actually get an NHS dentist; we try to ration by queue, then, appalled at the political costs of lengthening queues, we promise targets for waiting times for urgent care; then, abashed by the difficulties of meeting them, find ways of creating ghost queues waiting for the queue; then, dismayed at the distortions, we start “ring-fencing” this or that non-urgent area of provision too. And this, all of it, only an evasion of the truth that “free at the point of use” has become a declaratory, not an effective, administrative principle.

Laws are brought in, or proposed, to ban “hate-speech” against religions or homosexuality; then when challenged to explain how the free speech that the legislation's net seems to catch is to be protected, ministers insist that any prosecution would have to be approved by the Attorney-General. You realise, don't you, what they mean? There won't be any prosecutions - or very, very few; the Attorney will see to that. It was all about sending out a message.

We are, almost as I speak, renationalising the railways (via Network Rail), reimprisoning prostitutes (via ASBOs), regionalising rates of pay (via “housing” and “living cost allowances”), rewarding MPs on almost twice the scale the headline salary suggests (via allowances and reimbursements of every kind) and reneging on the Freedom of Information Act (via an increasing range of exemptions). We are increasing the amount of selection taking place in schools (selecting by parent rather than child, or by faith, or by “specialism”, or by house price). And we are reintroducing general powers of stop and search (via anti-terrorism laws). Yet all these things have been ostensibly abolished, often in ringing declarations in the House of Commons, and often - apparently - in legislation.

Making a law, then getting round it, may be thought by the marketing geniuses who exercise so much influence over modern politics to be a clever wheeze - getting the best of both worlds. But there is one law from which even the most cynical of declaratory lawmaking cannot wriggle out: the law of diminishing returns. If politicians choose to dwell only among declaratory headlines about the enactment of law, and duck questions about its execution, they foster first confusion and finally a general cynicism about the potency of politics itself.

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