Meet America's marijuana martyr

He's the Alan Titchmarsh of the pot world, with countless grow-your-own tomes and a licence to supply for medicinal use. But in what some are calling a Bush show trial, Ed Rosenthal now faces 40 years in jail

There are two reasons why the case of Ed Rosenthal has become a cause célèbre for the marijuana-decriminalisation movement. The first is that, for the past 30 years, he has been the world's foremost cultivator of cannabis plants, and a pioneer in hydroponic growing techniques. His many books – from Indoor/Outdoor Marijuana Growers' Guide in 1974 to the recently reissued Why Marijuana Should Be Legal – have been international bestsellers. And his advice column, "Ask Ed" – available online as well as in magazines such as High Times and Cannabis Culture – has come to be regarded as the Delphic oracle for pot-growers, the Gardeners' Question Time of getting high.

The second reason stems from the federal government's decision to swoop, without warning, on both his home and his hydroponic growing laboratory in Oakland, California in February last year. Rosenthal was charged with multiple felony counts of manufacture of an illegal narcotic, and put on trial at the beginning of this year. What the feds did not seem to appreciate – or care about – was that Rosenthal was growing his plants for the sole use of Aids, glaucoma and cancer patients seeking relief from pain. He did so at the behest of the city of Oakland, which in turn was acting in accordance with California's Compassionate Use Act of 1996 that permits the use of marijuana for medicinal purposes.

In other words, what he was doing was entirely legal, at least under Californian state law. But that was not something the court chose to share with the jury. Rosenthal's lawyers were not allowed to mention the 1996 Act, or the fact that he was acting as a formally enshrined officer of the city of Oakland. As a result, the jury felt obliged to convict him, even though several of them wondered during their deliberations just how much of a criminal he was. As soon as the trial was over and the full truth of Rosenthal's circumstances became clear to all, five of the 12 jurors staged an open revolt and demanded that he be granted a new trial. "Last week," one of the jurors, Marney Craig, wrote at the time, "I did something so profoundly wrong that it will haunt me for the rest of my life. I helped send a man to prison who does not belong there."

It has not quite come to that yet – he is not due to be sentenced until early June, and the controversy over his case is causing considerable ructions in the legal system that may yet keep him out of prison – but it is clear that Ed Rosenthal, on top of his previous celebrity status among marijuana cultivators, has become a symbol of all that is wrong and distorted about America's much-ballyhooed War on Drugs.

Essentially, he has become a pawn in an increasingly nasty battle between the federal government, with its virulently intolerant attitude to illegal drugs in all forms, and individual states, including California, that have sought to liberalise the laws around the edges by popular referendum. The federal government's attitude has become particularly unforgiving under the Bush administration, which, unlike any administration before it, has used paramilitary tactics to break up medical marijuana clubs, destroy plants kept by terminal patients, and arrest people such as Rosenthal who had no reason to suppose that they had fallen foul of the law at all.

"The feds are coming from totally insane places," an uncowed Rosenthal said in a phone interview. "A lot of people are frightened about what is going on in the US – and they should be. Is this Imperial Rome?"

What you think of Ed Rosenthal depends a bit on where you are coming from. If you are worried about the consequences of increasing marijuana consumption then he looks like the supreme irritant. As much as half of the cannabis consumed in Britain is now grown domestically, according to a new study by the Joseph Rowntree Foundation, and it's a fair bet that the growing fad for both garden and indoor cultivation has been fuelled by the impeccable advice offered by the pot world's Alan Titchmarsh.

It was Rosenthal who first guided the indoor-growing movement away from ordinary fluorescent lights to high-intensity discharge lights. He helped two generations of home-growers to regulate the nutrients required in a soil-free environment. More recently, he has pioneered the cloning of high-quality cannabis. None of this is good news if you believe that marijuana is a public-health hazard that needs to be eliminated through effective law enforcement.

On the other hand, if you believe – as many on both sides of the Atlantic do – that legal crackdowns on marijuana use do far greater social harm than the drug itself, then Ed Rosenthal starts to look like a veritable guru. As Oakland's official pot-grower, he was providing medical marijuana clubs with "starter plants" to provide high-quality product to the sick and dying. Nobody could have made pot more respectable – the very reason, he believes, why the Bush administration came after him. "I was a trophy arrest, and they were going to make a big example out of me," he said. "I think they have a special priority to try to stop medical marijuana. As the best-known person, I carry the greatest cultural impact."

In fact, the feds have gone after plenty of other people. Last September, the Drug Enforcement Administration raided a marijuana club in Santa Cruz, to the fury of the local authorities who have now filed suit in federal court demanding damages as well as an injunction to prevent the DEA from infringing on state affairs again. Then, in February, federal agents raided 100 homes around the country in search of bongs and pipe-making materials. They made more than 50 arrests, even though they found no drugs, and even though, in California and other states, possession of marijuana pipes is explicitly decriminalised.

Rosenthal is certainly correct, however, in saying that his arrest was the most spectacular. His treatment has been condemned not only by drug-reform groups but also by The New York Times and other newspapers. The judge in his case, Charles Breyer of the US District Court in San Francisco, has been forced to admit that the outcome achieved by a series of rulings favouring the prosecution may not stand up to scrutiny on appeal.

When Rosenthal heard banging on his front door in the early morning of 12 February last year, he thought his neighbour was in trouble. "Instead," he said, "I was greeted by the armed forces of the US, guns at the ready. They were expecting to find gold and big bank accounts. Instead, they found a middle-class family." (Rosenthal, who is 59, has a wife and two teenage children.) They handcuffed him and produced a search warrant based on apparently false assertions, including the suggestion that federal agents had been tipped off to the presence of marijuana by the smell. Starter plants, Rosenthal insisted in court documents that the judge refused to admit as evidence, have no smell; it is the flower buds that have the smell.

On top of denying him any opportunity to mount a defence, Judge Breyer also told the jury that they had no discretion in deciding whether Rosenthal was guilty. If he had grown the plants – and he clearly had – then they were obliged to convict him, even in the knowledge that his crimes carried a minimum sentence of 40 years behind bars. The five rebel jurors now believe that they were misled on that point, too. Jury nullification – the power to acquit a defendant if the government's position seems unjust – is enshrined in the Sixth Amendment, which characterises the jury as "the conscience of the community".

What Rosenthal's case shows is how the government's War on Drugs – rather like the analogous war on terrorism – can be used as an excuse to ride roughshod over every conceivable provision of the criminal-justice system, even the right of defendants to give their side of the story in court. As such, it stands as a cautionary tale to any country tempted, like the US, to take the hardline law-enforcement route on a soft drug. As Rosenthal writes in his latest book: "No law should be more harmful than the behaviour it seeks to regulate."

There are signs that the Bush administration has seriously overreached. Several Californian cities have passed resolutions urging police not to co-operate with DEA and FBI raids on medical marijuana facilities. It may all end up in the Supreme Court in Washington. Until then, Ed Rosenthal and his band of supporters will fight on. "These laws are going to come down," he vows, "and this case will be a part of it."