THE terrible suffering of Billy Caldwell, a 12-year-old boy with epilepsy, seems to have forced the government into a landmark concession over its drug laws. His seizures were controlled with a pharmaceutical-grade cannabis oil that is made in Canada. But when his mother tried to bring a supply into the country, it was seized by the Home Office. The law deems cannabis to have no medical value, and its possession has been illegal since 1971. When Billy was later hospitalised with a return of his seizures, Sajid Javid, the home secretary, relented and issued a 20-day licence for the product. Billy was then treated and released from hospital.

Despite the short length of the licence, Mr Javid’s move set a clear precedent for the medical use of cannabis in Britain. On June 19th he duly announced a change of policy, on the grounds that it had become apparent that there was a pressing case for letting people who might benefit from cannabis treatments have them. Within a week, the Home Office will set up a panel of clinicians to review requests for access to cannabis for medical use. Hundreds or even thousands of applications can be expected, most of them from patients suffering from epilepsy, multiple sclerosis or chronic pain.

The Home Office has also started a review of how the law treats cannabis for medical purposes. Since Mr Javid says the government plans to permit the drug’s use if it has significant medical benefits, and he has implicitly conceded that such benefits exist, a relaxation of the rules seems inevitable. When Sally Davies, the chief medical officer, reviews the evidence for the medical benefits of cannabis, she will find stacks of reports supporting its use in the management of pain, nausea and anxiety as well as epilepsy.

The way the law treats cannabis has become increasingly absurd. One component of cannabis, cannabidiol (sold as CBD oil) is available on the high street as a food supplement and has even been described as a medicine by the agency that regulates drugs. Another component, tetrahydrocannabinol (THC), is found in Sativex, a medicine prescribed to treat spasticity in multiple sclerosis—and made by a British company. A cannabis-based drug for epilepsy is also in the pipeline. Meanwhile, the medical use of cannabis is being legalised all over the world.

Crispin Blunt, a Tory MP and co-chair of a cross-party group on drug reform, thinks cannabis ought to become a schedule 4 drug. This category includes benzodiazepines, anti-anxiety medicines and steroids. Legalisation would mean that patients would not need to fear the law or be exposed to the illegal trade—along with strains of the plant that are used more for their mind-bending than their therapeutic potential. Patients would also be able to obtain pharmaceutical-grade products that are subject to strict quality control. And a change in the scheduling of cannabis would make research into its medical use far easier.

William Hague, a former Tory leader, suggested this week that cannabis ought to be legalised completely, as it has just been in Canada. He argued that the war against it had been lost. But Mr Javid insisted that his review should not be seen as a first step towards the legalisation of cannabis for recreational use. Even so, moves to legalise it for medical use will trigger discussions about the growing support for similar use of drugs such as LSD and MDMA in mental-health disorders.

There is little doubt that a change in the rules for cannabis will lead to more being used for recreational purposes. That has been the experience of other countries. However, drug diversion also happens with many other kinds of drugs, including ADHD medicines and opioids. Cannabis misuse by the young raises genuine concerns about links to schizophrenia. Yet the harm must be set against the medical benefits. And most forms of cannabis have a low potential for dependency—much lower than alcohol, for instance. The story of Billy Caldwell suggests that, unusually, a hard case will make good law.