Until a few weeks ago I thought a “get out of jail free” card was something you could only find on the Monopoly board. Now the British Government is handing them out for real, because the jails are full. In the first week of July 1,700 criminals were released early; 344 of these had been doing time for violence. Thirty have already broken the terms of their release and the police are still hunting 18, who have presumably thrown sixes and headed for rich pickings on Park Lane. But ministers seem more interested in interning terror suspects without charge than incarcerating convicted thugs.

It is a fundamental principle of British justice that punishment should be proportionate to the crime. To most reasonable people that means that the sentence served should be the sentence given. Forget it. Since the 2003 Criminal Justice Act, anybody sentenced to more than four years has automatically been eligible for parole in half that time. Now we are told that 25,000 people serving less than four years will be released early in the coming year. That’s quite a few burglars and drug dealers. Even if it’s only a few weeks early, it’s not justice as we used to know it.

Sentences have become meaningless, and there is only one reason why: the Government's refusal to build enough cells. For ten years they have found it expedient to ignore the warnings that more prison places would be needed. As Chancellor, Gordon Brown consistently dismissed the pleas of Home Secretaries who were rivals. All sorts of creative financing mechanisms were proposed to the Treasury, notably by my friend Hilary Cottam, who proposed a sale and leaseback of Wormwood Scrubs. I asked David Blunkett about that scheme four years ago. He had tried everything, he said. The Treasury simply would not listen.

There are famously no votes in prisons: the public does not much care about reprobates, as long as they are out of sight and out of mind. They do care, however, if they come out and start terrorising old ladies. The prison issue is an unexploded bomb for Mr Brown that must be close to going off with the new Prime Minister still holding it.

This makes the complacency all the more odd. In the Commons last week Nick Herbert, the Shadow Justice Minister, called the Government’s management of the prison system a national disgrace. Jack Straw claimed that Labour had created 20,000 new prison places, but then admitted that many of these “places” were achieved simply by crowding more men into the same old cells. He asked, triumphantly, whether the Tories would foot the bill for the 60,000 more places that would be needed if all inmates were to serve their sentences in full. So prisons are still being treated as a game, and justice is being warped by the price tag.

In the past three weeks, this Government has committed £8 billion to housebuilding and £600 million to higher university grants, without turning a hair. It has spent billions on “just” wars in foreign parts. It talks tough on crime. But it seems squeamish about actually protecting its own citizens from criminals.

If we cannot afford to make prisoners serve their full sentences, there is precious little point in having judges who are skilled in the intricate balancing of intent, remorse, and suffering. If the “correct” number of prison places is defined as the existing number, because the Treasury prefers to spend its money elsewhere, we might as well tell the courts to start turning cases away.

There is a marvellous combination of doublespeak and doublethink here. It is doublespeak when ministers claim that “releasing people on licence means that their sentence continues”. In whose world? These individuals are free to offend again. It is doublespeak when the Prime Minister promises to deport foreign prisoners, many of whom will be protected by the Human Rights Act and a 2004 EU directive. It is doublethink when a government that has created more than 3,000 new offences and a myriad of criminal justice Bills then refuses to accept that it will need somewhere to put the extra offenders it has created.

Prison overcrowding has several disastrous consequences. On Tuesday the Appeal Court ruled against the indeterminate sentences that ministers designed to keep sex offenders in prison until they were deemed fit for release. Overcrowding has made it impossible for some of these men to take the parole courses required for them to be considered for parole – a Catch22 that has rightly been challenged. So sex offenders who were given short sentences by judges who thought the minimum tariff didn’t matter are now likely to be freed.

The worst consequence of the Government taking liberties with the prison system is that it has dashed almost any hope of rehabilitation. Half of all crimes are committed by ex-convicts. Half of all prisoners have shockingly poor literacy skills. Some have mental difficulties and many are on drugs. But the Government has quietly dropped its key performance indicator of 24 hours a week of “purposeful activity” in prison. Some young offender institutions are providing barely an hour of education a day. That is not justice, either.

Governments can cover up incompetence in most public services. They can blame the staff, or ask for productivity to be measured differently. Crime and punishment are different. The first duty of any government is to protect the public. Britain is now a country that feels scared; it has read in the past week of a father playing cricket with his son being stoned to death by boys as young as 11, and of a schoolboy shot in the head while on his bike.

What will happen when the perpetrators reach prison? “Pass Go and collect £200”, like the other prisoners on early release? Ministers cannot go on treating this as a game.

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