John Stuart Mill once said, “Every great movement must experience three stages: ridicule, discussion, and adoption.” It looks like the movement to end the failed war on drugs is about to enter the second stage, at least on a political level.

For the first time since Richard Nixon launched the international war on drugs more than 40 years ago, a U.S. president will face sharp criticism of this policy from his Latin American counterparts at a regional gathering this weekend. The setting is the Summit of the Americas, which will take in Cartagena, Colombia, on April 14-15.

As the Washington Post reported this week, some Latin American presidents, led by Guatemala’s Otto Pérez Molina, will bring to the table a discussion on alternatives to drug prohibition, including legalization. To be sure, there is no consensus among Latin American leaders on this issue. However, it will be the first time such a discussion will take place at this level.

The Obama administration has said that a regional debate on drug legalization is “legitimate,” but that U.S. support for prohibition won’t budge. However, there’s some evidence that Washington is pressuring some Central American countries to boycott the efforts of Guatemala to discuss this issue. At least that’s what Pérez Molina said after the presidents of El Salvador, Honduras, and Nicaragua skipped a Central American summit a couple of weeks ago where the Guatemalan leader expected to rally the region behind his proposal.

Colombia’s Juan Manuel Santos, the host of the upcoming summit, is a critical figure in this debate. He was the first president to come out in favor of a debate on legalization, a policy he says he would support as long as everyone else agrees to it. That, of course, is a big caveat. Santos, while remaining critical of the war on drugs, has been more cautious than Pérez Molina in proposing and advocating legalization. However, as Santos himself has stated, Colombia has lots of moral authority to bring up this discussion.

The other important person to watch is Brazil’s Dilma Rousseff. High-ranking officials have said in the past that her government would explore alternatives such as decriminalization, but only after “deep” analysis. However, Rousseff hasn’t commented yet on Guatemala’s proposal. Because Brazil is the second-largest consumer of cocaine in the world, and is a diplomatic heavyweight in the region, its stand on this debate matters significantly.

Both the Rousseff and Santos administrations have pointed to the importance of having a “deep” and “objective” discussion about the merits of alternative drug policies. This means that the United States will no longer be able to dismiss the debate first-hand.

For decades the Cato Institute has been a leading voice for drug legalization. Our studies and conferences have provided facts and arguments on the futility of prohibition and the merits of alternatives such as decriminalization and legalization. We are gratified that the debate on ending the war on drugs is now reaching the highest levels of government, and plan to continue providing analysis for policymakers to make informed decisions.