Earlier this month, two US states voted to legalise, regulate and tax marijuana. The BBC's Will Grant in Mexico City looks at what this shift in stance could mean for Mexico and its fight against the drug gangs.
Every year, pro-marijuana campaigners in Seattle hold their annual Hempfest, a two-day festival along the city's shoreline.
Thick pungent clouds of pot smoke waft over the crowd who are sitting out with a joint in their hand, listening to the live music, or pottering among the dozens of stalls selling bongs, pipes and other smoking paraphernalia.
The police are on hand to ensure there is no open buying or selling of the drug. But at the next 'Hempfest', they may not even need to do that.
On the day voters in Washington state chose to re-elect President Barack Obama, they also chose to legalise the recreational use of marijuana. Over the Rockies in Colorado, it was a similar story.
"What happened in Colorado and Washington was truly revolutionary," says Beau Kilmer, the co-director of the Rand Drug Policy Research Centre in California. "No modern country has ever removed the prohibition on the production and distribution of marijuana for non-medical purposes."
When the measure comes into effect in Colorado in early December, it will be legal to possess 1oz (28g) of marijuana if you are over 21; it will be legal to grow up to six marijuana plants in your house; and it will be legal to give away up to 1oz.
There are still complex questions about creating a regulatory framework for the production and distribution of the drug, which may take at least another year.
Needless to say, such a move puts the two states on a legal collision course with the federal government and its drug enforcement policies. But Dr Kilmer believes it is a mistake to view the Obama administration as a single entity in this regard.
"At this point no-one knows how the federal government is going to respond to these two states. But it's important that we don't think of it as a homogenous actor."
The Drug Enforcement Administration (DEA), the US Attorney-General's office and the Internal Revenue Service (IRS) all have a degree of jurisdiction, and discretion, over these issues, Dr Kilmer points out.
Use of force
Meanwhile, thousands of kilometres away, in a "smoke shop" in Mexico City, the news of Colorado and Washington's decision has been warmly welcomed. Surrounded by glass cabinets full of expensive-looking vaporiser, the proprietor tells me that many of his customers are hoping for a similar law in Mexico.
"People don't want to contribute to the drug cartels' profits any more and I've sold a lot of copies of this recently," he says, holding up a book called The Ecological Cultivation of Cannabis.
The man in Mexico currently leading the charge to change the law is left-wing politician Fernando Belauzaran. He has introduced a bill in Congress along similar lines to the one in Colorado, which would bring marijuana under the same regulation as alcohol.
"What has happened in the US has moved things forward, because this debate is crucial," Mr Belauzaran told the BBC on the day he formally presented the proposal.
"We need to ask if it makes sense to carry on with this full-frontal military campaign which has generated so much destruction and death in our country in order to impede the entrance into the United States of a substance which is now permitted and regulated."
Mr Belauzaran does not necessarily expect his measure to pass in this legislative session. But what is important, he says, is the new discourse on the issue.
In some parts of the US and Mexican media, the decision in Washington state and Colorado has been called a "game-changer" in the bilateral relationship between Mexico and the United States on the war on drugs.
Both the outgoing administration and the incoming one in Mexico have indicated that they expect things to develop with respect to marijuana during President Obama's second term.
Hosting several central American leaders recently, Mexican President Felipe Calderon said the decision in the US was a "change in paradigm" on drug consumption. He called for the United Nations and the Organisation of American States to help clarify the situation.
The new government went even further.
"Obviously, we can't handle a product that is illegal in Mexico, trying to stop its transfer to the United States, when in the United States - at least in part of the United States - it now has a different status," Luis Videgaray, President-elect Enrique Pena Nieto's top adviser, told journalists.
But it is not just in Mexico that the debate on marijuana is shifting. Uruguay too, under left-wing President Jose Mujica, is moving to put the state in charge of regulating the cultivation and consumption of legal cannabis.
Continent-wide, there are obviously many discussions still to be had.
Advocates and opponents disagree about the extent to which legalisation of marijuana would hurt the drug cartels' profits - some quoting figures in the billions, others in the mere tens of millions. And there is still a long way to go before President Obama formulates a coherent response to the voters' decision in the two states.
But amid the smoke and mirrors, one thing seems clear: when it comes to marijuana in the Americas, the seeds of change have been sown.