Scotland has the highest drugs death rate in Europe, with narcotics claiming more than 100 lives on average every month.
The Scottish government is proposing to decriminalise the possession of drugs for personal use to "help and support people rather than criminalise and stigmatise them".
But the UK government, which controls drugs policy, has rejected the plan as dangerous and says it has no intention of giving the Scottish Parliament the power to enact the new policy.
So what is decriminalisation - and would it work?
In setting out their proposals, Scottish National Party (SNP) ministers cited Portugal, which relaxed its drug laws in 2001, as a potential model.
Despite having almost double the population of Scotland - 10.3 million compared with 5.5 million - Portugal has far fewer drug deaths. There were just 74 in 2021 compared with 1,330 in Scotland, where the figures for 2022 are set to be published on Tuesday.
The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) makes comparisons using drug deaths of people aged 15-64 years-old.
On that measure, National Records of Scotland says Scotland had 327 deaths per million people in 2020, the most recent year for which the breakdown is available, while the EMCDDA says Portugal had nine deaths per million.
Statisticians say there are some methodological differences between the two nations but the figures are broadly comparable.
Portugal's architect of decriminalisation, João Goulão, argues that adopting a similar policy in Scotland could save lives.
"We are dealing with a health condition, with a disease, and we do not criminalise other diseases," he tells BBC News.
We meet Dr Goulão in the Portuguese capital, Lisbon, at the General Directorate for Intervention on Addictive Behaviours and Dependencies, where he oversees national drugs policy.
Globally, many advocates of drug liberalisation praise the framework which the former GP helped to design.
In Portugal, drug trafficking and dealing remain criminal offences. Possession of up to 10 days' supply for personal use of any drug, including heroin and cocaine, is not criminal - but it is not legal either and is dealt with as an administrative matter.
If a user is detained, and if there is no evidence that they are supplying narcotics, the police can confiscate their drugs and refer them to a Commission for the Dissuasion of Drug Use. This is a panel usually made up of a legal expert, a health professional and a social worker.
There is one commission for each of the country's 18 districts. Overseen by Portugal's health, rather than justice, ministry, they try to establish if a drug user is an occasional recreational consumer or someone struggling with addiction.
The panels have a variety of options available to them, including referring the user for treatment or counselling; levying fines for repeat appearances; imposing sanctions such as revoking a driving licence, a gun licence, or the right to practise in a licensed profession; and applying restrictions on visiting certain places or associating with certain people.
However, in around four out of five cases, after a discussion with the user about their drug use, no action is taken.
In the last year for which figures are available, nine out of ten participants were male and 45% were aged between 16 and 24.
The number of people appearing before the commissions rose from 4,850 in 2002 to 11,995 in 2017 before falling back to 6,628 in 2021.
The head of the commissions, Nuno Capaz, says that reflects the changing rate at which police referred users, rather than a shift in drug use.
Dr Goulão says there have been challenges with funding and recruitment of staff in recent years which have made the job of the panels more difficult, but he insists Portugal is in a much better place than it was before decriminalisation.
Then, he says, the nation was in the grip of heroin and HIV epidemics, with drugs deaths running at around 350 per year.
At one point, one per cent of the entire population — some 100,000 people — had used heroin, estimates Dr Goulão.
"It was difficult to find a Portuguese family that had no problems related to drugs," he adds.
Illicit drug use had exploded after the overthrow, on 25 April 1974, of the right-wing Estado Novo (New State) dictatorship, in a peaceful coup which became known as the Carnation Revolution.
The restoration of democracy saw a closed, conservative and Catholic country rapidly opening up to the world.
It also led to the return of tens of thousands of Portuguese soldiers who had been fighting to retain colonies in Angola, Guinea-Bissau and Mozambique.
Luis Miguel Pereira recalls how, as the troops came home, drugs flooded into the country.
He started using at the age of 14, he says. Nearly four decades later, he is HIV-positive and remains hooked on cocaine and heroin.
"I need it," he says, simply.
As a child, Mr Pereira says, he had a good life, studying and playing football, "but when I start to take drugs, everything changes."
"It's like a prison," he says. "You are locked inside of the drugs. You wake up thinking drugs. You lay down thinking drugs. It's the only thought that you think in your mind."
By the late 1990s the left-wing government of António Guterres - who is now Secretary-General of the United Nations - had begun to take steps towards liberalisation. In November 2000, it passed law number 30/2000, which enacted decriminalisation from 1 July 2001.
"The initial impact was amazing," says Rui Moreira, who was running a nightclub at the time but is now the independent mayor of Porto. "It was great."
"It was very influential. We were giving them methadone. We were supplying them with medical help. We started controlling HIV. We started distributing free syringes through pharmacies."
These days the most obvious embodiment of this 'harm reduction' approach are Portugal's two drug consumption rooms, one in Porto which opened exactly one year ago, the other in Lisbon, which has been running since 2021.
In the Porto centre, co-ordinator Diana Castro explains that nurses, a psychologist, a social worker and a doctor are on hand to assist and advise users.
In just nine months, she says, it has helped 1,600 people.
"Every day we are saving lives," she added.
The mayor of Porto supports the facility and remains in favour of decriminalisation, but he tells us that he also has concerns.
Time, says Mr Moreira, has revealed some nasty side effects of law 30/2000.
First, he argues, it normalised dangerous drug use among young people, entrenching criminal behaviour by those desperate to feed their addiction and supporting profits for drug dealers.
And as hard drugs began to lose their stigma, users could even be seen shooting up outside schools - where it was forbidden to advertise ice cream or sweets, he adds.
These side effects are not everywhere, by any means. Many parts of this industrial powerhouse turned tourist hotspot on the Douro estuary are bright, clean and bustling with visitors.
But look for evidence of drug taking in Portugal's second city, and you can certainly find it.
Outside São Bento railway station, in the historic centre of this Unesco World Heritage site, syringes lie discarded on the cobbles.
A short drive away, a group of drug users, stripped to the waist, huddle in the shade under a public stairway.
And in Porto's noisy margins, under the flight path of Francisco Sá Carneiro airport, the atmosphere outside the drug consumption room in the neighbourhood of Pasteleira is edgy, as Tony prepares to smoke crack cocaine.
"I'm here every day," he tells me, in his native Portuguese.
Tony's aquiline features and grey curls lend him the air of a senator in Ancient Rome.
But given that Tony, 61, says he has been taking drugs for 40 years, perhaps his most remarkable feature is a beating heart.
"I only do coke," he says but then adds: "I take methadone. And I only take heroin when I run out of methadone."
"Even if the law decriminalises consumption… the police are very aggressive with us," adds Tony.
"We're treated like garbage. It's not fair."
Not long after chatting to Tony outside the facility, our guide tells us abruptly that we must leave.
A look-out has apparently summoned a more senior member of a drug trafficking gang and Pasteleira is no longer considered safe for us or for those with us.
We return to the area a few hours later, accompanied by Porto's municipal police chief, Superintendent Antonio da Silva. He takes us to a rabbit warren of a housing scheme, its high walls crisscrossed by shaded alleyways.
A few months ago, says Mr da Silva, standing here would not have been possible.
"This was a stronghold of drug dealing in Porto," he explains, describing it as a "complete nightmare" full of dealers and users.
Faced with angry residents who felt trapped in their own homes, the national police moved in and cleared out the criminals.
Drug trafficking is a "big problem" in Portugal says Commander Rui Mendes, head of Porto CID at the national police force, which carried out the operation.
"The traffic dealers are very well organised," he adds.
"You can make 500 arrests but sometimes I feel you can do a thousand and it would be the same because the profits are too high for them," says Mr Mendes.
Mr da Silva supports decriminalisation but he agrees that the fight is never ending. Asked if the operation in Pasteleira simply pushed the problem elsewhere, he replies: "Definitely."
"We can make arrests," he adds, but "the police will not solve the social problem of drug addiction."
The drug consumption room in Lisbon, like its counterpart in Porto, is also under a noisy flight path on the margins of the city, with drug users sheltering from the blazing sun beside a dual carriageway, barely visible in shadows cast by concrete and steel.
Roberta Reis, who runs it, agrees with Mr da Silva that decriminalisation has worked. "A history of success," is how she describes the policy.
Ms Reis says harm reduction has led to a fall in cases of hepatitis B and C, tuberculosis, and HIV.
"You can educate people to use [drugs] in a safer way," she adds.
This is a common view here. Decriminalisation feels settled in Portugal. There is no mainstream call for the policy to be reversed.
The mayor of Porto, Rui Moreira, does want changes though. As well as improving housing, cleaning up public spaces, and offering more opportunities for young people, he is calling for criminalisation of drug use in certain areas, such as near schools and civic centres.
There are limits to the comparisons between Portugal and Scotland. No two countries are the same. Scotland has a particularly acute problem with benzodiazepines.
The outgoing chief constable of Police Scotland, Sir Iain Livingstone, recently told Today on BBC Radio 4, that officers had, in effect, been operating a de facto decriminalisation policy.
"For many years now, those that use drugs and addicts have not been subject to criminal sanctions," he said.
"My greater concern," added Sir Iain, "rather than the decriminalisation of drugs, is actually making sure there's enough support services."
On that point at least there appears to be some agreement.
Antonio da Silva recalls being "absolutely shocked" by Scotland's death rate.
"Scotland is by far the worst… It's something that should make us think about what is going wrong there," he says.
"Must do something," agrees João Goulão, although he has a word of caution for policymakers in Edinburgh and London.
"Decriminalisation by itself gives you nothing," he warns, "but all the health responses — treatment, harm reduction — are much more efficient within a decriminalised environment than they were before."