On Wednesday, after 13 hours of contentious debate, the lower house of Uruguay's General Assembly narrowly approved a landmark marijuana-legalization bill, 50 to 46. The Senate, controlled by a bigger majority of the ruling center-left Frente Amplio (Broad Front) of President Jose Mujica, is widely expected to pass the bill, and Mujica will sign it, putting it into effect as soon as this month.

When that happens, says Ignacio de los Reyes at BBC Mundo, "this will become a groundbreaking law, but not only for Uruguay." Tens of thousands of Latin Americans have died over the past few decades because of drug trafficking, and Mujica is one of a growing number of Latin American leaders convinced that legalizing some drugs is a more effective way to undermine the cartels than the U.S. method, which is "heavily dependent on law enforcement and prohibition."

"This is a very innovative bill, with the state deciding to regulate the entire chain of production, distribution, and access to the substance," Laura Blanco, president of Uruguay's Cannabis Studies Association, tells The New York Times.

Individual households will be able to grow up to six pot plants for personal use, or people can join marijuana co-ops, allowed 99 plants. Private enterprises can grow marijuana, but their only customer will be the government, which will sell the crop at specially licensed drug stores. To buy up to 40 grams a month at one of these pharmacies or grow their own, Uruguayans have to sign up on a confidential federal registry. Foreigners and minors will not be allowed to participate.

The proposed law is a lot like those passed in Washington state and Colorado, says Manuel Rueda at Univisión/ABC News. "Except that this is a national law, which will make Uruguay the first country to fully legalize weed." If you're thinking, "What about Amsterdam and the Netherlands?" Rueda says, the Dutch have "decriminalized consumption but not production or commerce," even if they tolerate those activities.

The idea behind Uruguay's legalization push — and why it will be closely watched by its neighbors and even the U.S. — is that it "can help to push criminal groups out of the marijuana market by offering pot smokers a product that is cheaper and better than what they can find on the streets," says ABC's Rueda.

In that sense, it's sort of like the Spotify of drug policies: If you give people a legal means to get what they want (like music or marijuana) at what they consider a fair price, they will give up obtaining the goods illegally.

The arguments against the law will sound familiar to anyone who has followed the pot-legalization debate in the U.S. Marijuana is a "gateway drug," says Gerardo Amarilla of the opposition National Party. "Ninety-eight percent of those who are today destroying themselves with base cocaine began with marijuana.... I believe that we're risking too much. I have the sensation that we're playing with fire."

The counterargument is also familiar: The "drug war" isn't working. Sure, Uruguay, with 3.3 million people, hasn't been "beset by the plight of drug-related violence seen in Mexico or Central America," says Juan Carlos Hidalgo at the Cato Institute. But it is taking "a momentous step in the road to dismantling the international prohibitionist regime that has been in place since the 1960s."

Marijuana legalization bills have already been introduced in the legislatures of countries such as Chile and Mexico.... The Obama administration faces a choice: It may either obstruct the momentum toward reform, or it may engage Latin American countries in an open debate about how to end a failed policy that has cost the lives of hundreds of thousands of people in the region. That would be change we can believe in. [Cato]

There are limits to what pot legalization can do, and proponents shouldn't "oversell" the benefits, says John Walsh at the Washington Office on Latin America think tank. Uruguay's law should "offer improvements on a whole range of measures, like reducing the revenues of criminal groups, reducing incarceration levels, and probably reducing violence," Walsh tells ABC News. But it won't completely solve any of those problems.

Recent opinion polls show that Uruguayans aren't sold on the law, with about two thirds opposed. But opinion has shifted pretty quickly in the U.S. — a majority now backs legalization — and it could do the same in Uruguay. Maybe Uruguay's government should study how the successful movements to legalize pot via the Washington and Colorado referendums brought public opinion to their side. The U.S. should learn a lot from Uruguay's experiment, too.

The tough stance against pot stems from the Nixon administration, when it was tied to countercultural lefties, but "we have progressed, we have evolved, and all the dangerous things that were said about marijuana didn't come to be," former DEA intelligence officer Gary Hale tells ABC News. Now, pot "legalization is an inevitability, it's something that will happen whether we like it or not."