When you call the Home Office and ask them to comment on a drug story, you always get the same response. They have a boilerplate statement which they stamp on any drug report they can get their hands on. Their drug strategy is working. Use is falling. They will continue to protect hard-working British families from the perils of drugs. You know the line. You've heard it a million times before. It's there at the end of every drugs item in every newspaper: the obligatory Home Office spokesman coda.

So it's always interesting when a new Home Office argument emerges, as it occasionally does. The most recent, made for the first time by Home Office minister Mike Penning, is remarkable for two reasons: Firstly, it is insane. Secondly, it appears to have been lifted from a cannabis legalisation website.

The argument features in a letter he sent to business secretary Sajid Javid. Javid had just had a meeting with one of his constituents, Rosemary Humphries, two of whose sons died from heroin overdoses. She is now a campaigner for drug law reform.

Javid behaved impeccably. Despite his busy schedule and ministerial responsibilities, he held a long meeting with Humphries and then passed on her concerns about drug policy to Penning.

The Home Office minister's behaviour was not quite so impeccable. His letter starts with all the usual boiler-plate arguments. He says "drugs are illegal where scientific and medical analysis has shown they are harmful to human health", ignoring the fact that he has just presided over legislation banning drugs regardless of whether they are harmful to human health or not. Although, to be fair, he didn't seem to understand the bill when he was describing it to the Commons, so it's possible he still doesn't.

"Our legislative approach and wider response continues to be updated with the support of our independent experts, the Advisory Council on the Misuse of Drugs, and evidence collated through UK and international drugs early warning systems about emerging threats," he goes on to say. Of course, what the Home Office has really done is sideline the Advisory Council, precisely because its independent expertise so often contradicted Home Office policy.

But these are all old well-worn arguments which we've heard many times before. Things get interesting when, out of nowhere, a new argument emerges.

"ln addition, a substance that is considered harmful cannot be produced and distributed with the help of the state."

This is staggeringly inane. There are many potentially harmful substances produced and distributed with the help of the state. Nicotine, fertiliser or uranium, to name just three. It's hard to believe that anyone with a trace of intelligence would ever be able to make this claim without realising that it is plainly untrue, much less send it to a grieving mother.

He then adds:

"The duty of every responsible government is to protect its citizens' health and not to expose them to risks, which could place their health and safety at risk through the proliferation of harmful drug use in UK society."

If you search for this argument online, something odd happens. It appears on only one website, in more or less an unchanged form from the manner in which Penning expresses it. And that website, wonderfully enough, is an American pro-cannabis legalisation website – legalizationofmarijuana.com- in which the writer tries to construct arguments against drug law reform. The first argument the author comes up with is:

"State cannot be involved with the distribution of substances considered immoral by relevant lots of the population. A substance considered unhealthy cannot be produced and distributed with the help of the state, because the goal of the state is to protect citizens’ health and not to expose them to risk."

It's really very similar indeed to Penning's sentence. So much so that it is hard to escape the idea that someone in the Home Office has been Googling 'arguments against drug legalisation' and copying-and-pasting them into letters to bereaved parents.

As Danny Kushlick of drug law reform group Transform says:

"The Home Office reply demonstrates utter contempt for Rose, who deserves so much better, but also for her MP, Sajid Javid, who, as business secretary, well knows that government regulates all kinds of harmful substances. Indeed that is exactly Rose's point. As the mother of two children who died from heroin overdoses, she wants drugs regulated by government precisely because they're dangerous. The fact that the specific line arose from a quick internet search serves only to add insult to injury."

Kushlick is right. The standard of this letter is well below that which a grieving parent deserves. It is shoddy, muddle-headed and lazy. And in that way it reflects very accurately the policy it is intended to defend.