Since then, Latin America has agreed, usually in exchange for US aid, to the rules of the game: an aggressive stance toward coca eradication and against narcotics trafficking.
Now, it seems, countries are beginning to back down from the punitive status quo and embracing the decriminalization of illicit drugs for personal use.
To be sure, Washington still finds many on its side. Many of Latin America's politicians, nonprofits, and citizens are questioning the merits of decriminalization, and all countries still strictly forbid the legalized production, transport, and sale of illicit drugs.
But many in the region are now defying the long-established American mindset, even in countries that staunchly align with its security goals. That includes Mexico, where small amounts of cocaine, heroin, and marijuana for personal use were decriminalized just last month.
"I think there is a real fatigue with the US-style drug war ... a sense that the criminal penalties that the US has seen fit for itself, and also pushed for other people, aren't viable," says John Walsh, senior associate for drug policy at the Washington Office on Latin America.
Some countries in Latin America have long had far more lenient policies than the US. According to The Netherlands-based Transnational Institute, which culls data on national drug legislation, Uruguay, for decades, has left it to judges to determine whether intention is for personal use (which is legal) or sale (which is not), while as far back as 1998, Paraguay passed a law exempting punishment for those caught with 2 grams or less of cocaine or heroin and 10 grams or less of marijuana for personal consumption.
In 1994, a Colombian court declared it unconstitutional to punish those possessing small amounts of drugs intended for personal use, although Colombia's conservative President Álvaro Uribe – Washington's key ally in the region – has pushed to effectively reverse the decision with a constitutional amendment.
A spate of leniency
A new flurry of judicial and legislative action has emerged in recent months.
A week after Mexico's decriminalization law went into effect, Argentina's Supreme Court ruled unconstitutional the arrest of five youths found with a small amount of marijuana, a ruling that opens the door to drug law reforms in Argentina.
"Conceptually, the most important thing about [Mexico's new law] is that it distinguishes between consumers and criminals," says Jorge Hernández Tinajero, the president of Cupihd, a civil group in Mexico that disseminates information about drug policies.
A reformed drug law in Ecuador, which approved a new Constitution in a referendum last year that states that drug users should not be penalized, is expected this year. The draft is also expected to reduce sentence levels for small-scale traffickers, known as mules. And this year in Brazil, where environmental minister Carlos Minc has spoken often and openly against drug prohibition, the Ministry of Justice is preparing a law that is expected to fully decriminalize drugs for personal use. This comes after legislation in the past few years led prison sentences to be replaced by educational measures, the Transnational Institute reports.
Cooperation in US drug war wanes
The moves to decriminalize drug use come as left-leaning countries in the region are making it much harder for the US to carry out its drug war, which they see as wrongheaded.
Venezuela has been singled out by the US for not cooperating fully in its anti-drug efforts, while Ecuador decided to close the Manta air base to US operations after a decade of use.
That move caused the US to go forward with a controversial plan to use seven bases in Colombia for antinarcotics operations in the country, but it has drawn fierce criticism from nations around the region that worry that the mission could expand beyond Colombia's borders.
For some, moves in Latin America could set a dangerous precedent.
"I think that it is a very slippery slope when you loosen up on drug enforcement," says Roger Noriega, a former assistant secretary of State for Western Hemisphere affairs. "The proof will be whether [governments] lose control of security and well-being in their own countries. Will they lose traction vis-à-vis criminal networks that will be able to have space to operate within a legal economy?"
Part II: Legalization of drugs spreads in Latin America. Will the US follow? Click here to read the story.