The government may not mean to kill people with mental disabilities but it's deeds, not motives, that matter, and when the coalition subtracted political cost from economic gain, it found those with disabilities were the easiest people in Britain to dispose of.

Mental health is the NHS's Cinderella service, even in good times. In recession, it's hammered. Simon Stevens, the new chief executive as NHS England, has given us his priorities. He gabbles that he wants to "future proof" the NHS "against challenges ahead".

In plain English, he means cut budgets. He will insist on exceptions, of course, most notably for Britain's ageing population. No one dissents because we will all be old one day. It is harder to raise a tear for the mentally ill. We pity the "victims" of ageing and conventional illnesses and talk of their "bravery" because we can imagine ourselves in their position. Few talk of the victimhood or bravery of those who must live in a world where they are routinely bullied and despised.

Mental health trusts must save almost 20% more than conventional hospitals. Places of safety are vanishing, and people who ought to be mentally disabled patients are the inmates of the one British institution that treats them with greater disdain than the NHS.

Louis XIV's finance minister Jean-Baptiste Colbert said the art of taxation lay in "so plucking the goose as to obtain the largest amount of feathers with the least possible amount of hissing". The same applies to cuts.

Reduce most budgets and vested interests hiss. But the public applauds the politician who makes prisons meaner places. They are tough guys: alpha wonks. They make damn sure that crime doesn't pay. The prison population has doubled from 41,800 in 1993 to 84,000 today. In our macho times, the courts incarcerate vast numbers of minor offenders – 37,527 served sentence of six months or less in 2013.

The judiciary's treatment of women is particularly scandalous. Sixty per cent of all women in prison in 2013 were incarcerated for minor offences. Feminists condemn a misogynist judiciary, but in the 1990s, when the there were more men on the bench, the judges were less likely to jail women for trivial reasons and worried about what would happen to their children.

Today, some 200,000 children a year in England and Wales have a parent in jail. It is not only misogyny. Across the board, English law, English politics and English society have turned sour. The money did not follow the expanding prison population, even in the boom. Prisoners don't vote, and there never have been votes in treating them fairly. Civilised conditions depend on the conscience of the political class, and an examination of Britain's criminal justice system teaches us not to put our trust in that.

The coalition proved it did not want its coercive state exposed when it stopped prisoners receiving legal aid to judicially review inhumane conditions. Chris Grayling and the Ministry of Justice no longer fear accounting for their behaviour in open court, where all can hear them. Yet charities chip away, and last week the Prison Reform Trust issued a summary of what we can know with certainty. It presented a list of facts without comment. Do not let its brevity deceive you. Like the list of names on a war memorial, the repetition of uncontested truths has more power to move than a thousand polemics.

Since the financial crash, the National Offender Management Service has reduced spending by 25%. It has done it by making fewer prison officers cover more prisoners – the staffing ratio has fallen from one prison officer for every 2.9 prisoners in 2000 to one for every 4.8 prisoners now. It has done it by closing local jails and opening vast super-prisons, where inmates can be warehoused like shrink-wrapped meat.

Everyone knows the best way to encourage offenders to go straight is to allow their families to visit. The Ministry of Justice's own research suggested the likelihood of not reoffending was 39% higher when partners and children were at hand. Yet still it holds 30% of children 50 or more miles away from their homes. It cuts by tolerating an intolerable level of violence – in 2013 there were almost 11,000 attacks by prisoners on other prisoners and 2,731 assaults on staff. And it cuts by using punishment as a cost-cutting measure.

Specifically, the Justice Department is putting ever greater numbers of prisoners on its "basic" level, denying them what it calls privileges and others call common decency. "I am 65 years old and work full time or else I won't have any money," wrote one inmate to the Prison Reform Trust. "Really I am one of the lucky ones. Some of the prisoners are disabled, 70, 80 years old, locked behind their doors, no TVs, some have no radio, banged up at 5.30 evening until 10, 11am next day with no hot water."

Those least able to cope are those mentally disabled people Britain shuffles off to jail. Out of sight is out of mind, and they can go out of their minds without bothering the rest of us. A quarter of children in the criminal justice system are statemented.

Forty-six per cent of women prisoners said they attempted suicide at some point in their lives, and many succeed when they are in jail. In 2013 there were 215 deaths in custody, higher than any year on record.

Here from Inquest, a noble charity, which helps the families who die in the state's "care", is the last story we know of : the case of Jake Hardy, a 17-year-old, whose many psychological disorders were well known to the state.

He wasn't a serious criminal but the courts sent him to Hindley young offenders' institution for six months for assault and affray. The coroner found that boys on the wing bullied him. Staff knew he was "getting grief" but did nothing. Jake cut his wrist. Again nothing happened. He hanged himself, and a note by his body read: "so mum if you are reading this I not alive cos I can not cope in prison people giveing [sic] me shit even staff."

One might have hoped that with a prime minister who said that harrowing experience had taught him how "precious" the NHS was, Britain's Jake Hardys would have a friend in Downing Street: a politician who would insist that his ministers protected the vulnerable, however unpopular they were. They don't.