Walter Oi was an extraordinary economist with an extraordinary life. Detained during the United States’ shameful internment of Japanese-Americans in the Second World War, Oi’s later career triumph arguably left a deeper mark on American society than even that dark episode. Despite being blind, Oi provided the intellectual ballast that eventually helped to end America’s military conscription, known as “the draft”.

It upsets Conservatives to state it plainly, but Rishi Sunak wants to reintroduce a form of conscription in the UK. No, he doesn’t want to send kids to a modern-day Vietnam War. Under the Tory plan, only 30,000 18-year-olds will compete for military roles in cybersecurity, logistics, procurement or civil response. The rest of the 745,000 18-year-olds (by today’s count) would be forced merely to “volunteer”, which is Orwellian doublespeak for mandatory community service of a duration usually reserved for offenders.

In reality, that means 25 days a year at weekends in roles like delivering prescriptions, supporting fire and ambulance services or providing social care. It’s clearly not charity. It is state-mandated enlistment for community service. Pointing out that other northern European countries do it doesn’t change the fact that it remains a form of conscription.

This makes Oi’s economic case against conscription from the late 1960s and early 1970s a useful lens of analysis. Mandated roles force young people into work that they would reject voluntarily at such low pay, Oi observed. With a stream of draftees, the government also can offer lower wages to entry-level military staff, ambulance support workers and others presently undertaking those tasks that youngsters would be assigned to.

This creates a hidden tax on low-paid military and care personnel, equal to the difference between their existing wages and what the government would need to pay to attract them voluntarily. This tax, as Oi realised, means that the social cost of conscription is much higher than the £2.5 billion fiscal cost of the Tory scheme. The burden falls on the young and on entry-level public services workers.

“National service” is not an additional new “opportunity”, whatever Sunak claims. About 23 per cent of Britons aged 16 and 17 already have jobs. A third of those aged 16 to 24 volunteer and 36 per cent of 18-year-olds entered higher education in 2023. For young people, losing one weekend a month for a year has a hefty price: the opportunity cost of time otherwise recovering, studying, working for pay or volunteering according to their own tastes.

Nor would the effects of conscription be limited to conscripts. Presuming that national or community service tasks aren’t purely “make work” schemes, drafted labour earning modest amounts or stipends would compete with voluntary staff, driving down the latter’s wages. It’s like a constant penalty on special constables, on-call firefighters, emergency health responders and flood defence workers, roles that James Cleverly, the home secretary, said conscripts might undertake. Public services workers thus end up effectively penalised to support this scheme’s broader goals.

It is tempting to think that this means cheaper public services, a nice side-benefit alongside any transferable skills, community spirit or discipline picked up by the unruly young. But Oi’s empirical work shredded this notion, too. Lower pay makes full-time roles less attractive, leading to higher staff turnover. Add the yearly influx of 18-year-olds and you need more overheads for training, supervision and logistics, running a less efficient operation and making most savings illusory.

Thus far the Conservatives have dodged details on pay rates and exemptions to their scheme, with the promise of a royal commission disabling a thorough analysis of the costs and benefits. But Oi’s insights remain clear: conscription imposes a hidden penalty on the young and public-spirited. A coercive service mandate distorts the labour market, steals time from the young and cuts pay for junior staff in core public services. You need a wildly optimistic view of how state-enforced servitude can foster national spirit and community cohesion to make up for these downsides.