(CNN) -- The Argentina Supreme Court ruled Tuesday it is unconstitutional to punish an adult for private use of marijuana as long as it doesn't harm anyone else.
Argentina becomes the second Latin American country in the past four days to allow personal use of a formerly illegal drug.
The seven-member Argentina Supreme Court decision was unanimous, the court's Web site said.
The case in question involved five young men who were arrested for having a few marijuana cigarettes in their pockets.
Supreme Court Justice Carlos Fayt, who at one time supported laws that make personal use of marijuana illegal, told the state-run Telam news agency that "reality" changed his mind.
Argentina's action came amid growing momentum in Latin America toward decriminalization.
Mexico enacted a law Friday that decriminalizes possessing low quantities of most drugs, including marijuana, heroin, cocaine and LSD.
Earlier this year, a Brazilian appeals court ruled that possession of drugs for personal use is not illegal.
Peter Hakim, president of the Inter-American Dialogue policy institute in Washington, sees the shift in attitude toward drugs as recognition that current policy is not working.
"It's all part of a harm-reduction approach," Hakim said, noting that policy is shifting toward figuring out how to reduce harm to the users and to society.