For much of my adult life I’ve had to rise each morning and battle multiple sclerosis. Sometimes it’s a thankless task – my legs scissored together, locked in spasm as I fight to break free of its stranglehold.

I’m convinced cannabis has allowed me to live more of a normal life than would have been possible with the constant pain. I’ve always smoked it. But in recent years I’ve been making cannabis oil and turning it into tinctures. A few drops of my special brew numbs any niggling aches, clear my mind and help me get a good night’s sleep, spasm-free.

But smoking a joint or making cannabis tinctures could land me in jail for five years under our current drug laws. For someone living with MS or any other affliction that can be soothed by cannabis – including Parkinson’s disease, post-traumatic stress disorder or cancer – the stigma of a criminal record is not ethical or fair.

Since the “war on drugs” was launched in the early 1970s millions of people with medical problems have been getting a bum deal. Cannabis, for centuries lauded for its therapeutic benefits, was unjustly demonised, tossed in with the likes of heroin and cocaine, to be expunged from the reach of society. However, the war was lost long ago. It is estimated that the illegal global drug market is worth about $400bn a year. The figure represents the total failure of the policy and excludes the billions wasted fighting it.

Several UK police forces, including Durham, effectively decriminalised the personal use of cannabis to prioritise resources. And public opinion supports a change in the law, especially when it comes to medical cannabis. That is only likely to increase after the fight by the mother of a six-year-old boy with a rare form of epilepsy who has been refused a licence to be treated with cannabis oil.

People are just being held to ransom by an outdated law

Changes in the law in parts of the US, Canada and Germany mean that the use of medical cannabis is now legal there. The shift in policy has given people the opportunity to choose their medical path, allowing many to escape addiction to prescription opioids.

The UK government appears reluctant to follow suit. Yet since 1998 it has licensed GW Pharmaceuticals to produce Sativex. The medicine, for people with MS, is derived from cannabis plants, mostly grown by British Sugar. It is a step forward, but ultimately it has ringfenced the development and sale of medical cannabis at a massively inflated price. Only a handful of those with MS receive it: the National Institute for Health and Care Excellence (Nice), which authorises the use of drugs by the NHS deems it too expensive (a year’s supply can cost upwards of £5,000). You either have to live in parts of Wales or be able to afford a private prescription to benefit.

The formula in each 10ml Sativex bottle includes the chief components in cannabis – THC and CBD (2.5mg of each). It costs £125 a bottle and lasts on average 10 days. In comparison an ounce of medical cannabis will cost me £250 and hold upwards of 900mg of each component. Once extracted into cannabis oil and dosed accordingly, it can produce about 350 bottles of a product that does the same job, at a fraction of the cost.

Obviously by making the spray I am breaking the law – but it helps indicate the hypocrisy of the government’s stance and its inertia in facilitating real reform. The production process is certainly not rocket science, and cannabis is a common herb in many countries, and should not cost an arm and a leg. People are just being held to ransom by an outdated law.

Much rests on the second reading of Paul Flynn’s private member’s bill on Friday advocating cannabis be made legal for medical use. If it eventually passed into law, it would be a landmark day for people living with a chronic disease or in constant pain.

Big pharma and major corporations involved in the industry such as British Sugar may balk at a regulated free market in medical cannabis, seeking to protect their interests. The drugs minister, Victoria Atkins, has shown antipathy for any kind of reform to the laws on medical cannabis. (Incidentally her husband Paul Kenward, is the managing director at British Sugar.)

Flynn has got a lot of backers in his corner, though. Legalising medical cannabis might be personal to me, but it should be personal to us all. There are more than 11 million people living with a disability in the UK, and an ageing population means few will be immune from the pain that lies ahead. The benefits seen from the US and across the world offer us a template to build upon.

• James Coke is a writer. He blogs at thedisabledchef.com