This week, drug policy reform will be a major focus at the UN General Assembly, with at least four heads of state expected to call for major global drug policy reform.

One year ago, the presidents of Colombia, Guatemala and Mexico made headlines at the UN General Assembly by calling for alternatives to the war on drugs. Since then, Colorado and Washington became the first U.S. states – and the first political jurisdictions in the world – to legalize the production, distribution and sale of marijuana for adults. Uruguay is likely to join them soon – the country’s House passed a marijuana legalization bill in July and its Senate is expected to follow suit in October. This afternoon, Uruguayan President José Mujica will attend and address the UN General Assembly for the first time.

“More and more governments appear to recognize the need for a new direction in global drug policies,” said Ethan Nadelmann, executive director of the Drug Policy Alliance. “Importantly, we now have presidents in Colombia, Guatemala and Uruguay who are willing to push the envelope in challenging the failed prohibitionist regime.”

There will also be a series of closely-watched behind-the-scenes meetings between heads of state. Guatemalan President Otto Pérez Molina will hold separate meetings on Thursday morning with President Mujica (11:15-noon) and New Zealand Prime Minister John Key (10:30-10:50 am). New Zealand’s Parliament enacted a first-of-its-kind law this summer that will regulate and control – rather than criminalize – new synthetic drugs. President Pérez Molina will address the UN Assembly at 12:30 on Thursday afternoon.

In recent years, debate and political will for drug policy reform has gained unprecedented momentum in Latin America. In 2011, Kofi Annan, Paul Volcker, George Schultz and Richard Branson joined former presidents Fernando Henrique Cardoso (Brazil), César Gaviria (Colombia) and Ernesto Zedillo (Mexico) and other distinguished members of the Global Commission on Drug Policy in saying the time had come to “break the taboo” on exploring alternatives to the failed war on drugs – and to “encourage experimentation by governments with models of legal regulation of drugs,” especially marijuana.

More recently, current presidents – especially Santos in Colombia and Pérez Molina in Guatemala – have boldly sought to open the broader regional and global debate over alternatives to drug prohibition. Mujica, meanwhile, has provided that debate with a new level of urgency and momentum by becoming the first Latin American president to propose marijuana legalization.

In May, the Organization of American States produced a report, commissioned by heads of state of the region, that included marijuana legalization as a likely policy alternative. The OAS report predicted a likely hemispheric move toward marijuana legalization in the coming years.