Uruguay’s government-proposed marijuana legalization drive has been described as the world’s boldest, and could help reduce drug-related crime, but a conversation I had this week with former Uruguayan President Julio Maria Sanguinetti left me wondering whether it won’t backfire.

Under the bill passed last week by Uruguay’s Chamber of Deputies, which is widely expected to pass the Senate and become law very soon, Uruguay will legalize the farming, distribution and sale of marijuana. Marijuana consumption was already permitted in the country.

What’s more, the state will become the country’s largest marijuana dealer: It will give out licenses to growers, buy their marijuana, and distribute it to pharmacies around the country, where previously registered consumers aged 18 and over will be allowed to buy the equivalent of 30 cigarettes a month. In addition, Uruguayans will be able to grow up to six pot plants at home, and to create “consumer clubs” of up to 45 members, who will be allowed to sell the drug to one another.

As somebody who generally supports marijuana legalization drives, and who agrees with Uruguay’s President Jose Mujica about the need to find alternatives to the war on drugs that has left tens of thousands of dead in Latin America in recent years, I asked former president Sanguinetti — a government opponent — about his reasons for opposing the bill.

Interestingly, his first criticism was not so much about legalization itself, but about the party-like atmosphere in which it is taking place. He fears it will lead to a generalized increase in drug consumption.

“They have created a joyous atmosphere and a climate of permissiveness around marijuana, when, in fact, it’s known that it is very harmful,” Sanguinetti told me. “Its effects are not immediate, like those of cocaine, but it the long run it harms your brain.”

Most Uruguayans oppose the bill, among other things because they fear it will increase marijuana consumption among the young, and could drive youths to move on to harder drugs. According to a new survey by the Cifra polling firm, 63 percent of Uruguayans oppose the bill, while only 26 percent support it.

Pedro Bordaberry, a leading opposition senator, told me in a separate interview that he is skeptical that the government will be a responsible manager of the marijuana business. Uruguay already has a big problem enforcing its existing laws, he said.

“The government prohibits the resale of soccer tickets, and yet there is a huge resale of tickets in our country,” Bordaberry told me. “If they can’t control the resale of soccer tickets, will they be able to control the resale of marijuana?”

He added, “How will they keep a non-consumer from buying his 30 cigarettes a month, and then reselling them on the street? And how will they control that he doesn’t sell them to a minor?”

Supporters of Uruguay’s bill say the state already has a big role in regulating the marijuana industry in the Netherlands, Portugal and in Colorado.

“There are always dangers, such as the possibility of more bureaucracy, and bribery,” says Bruce Bagley, a well-known drug policy expert with the University of Miami. “But most states are already involved in regulating, monitoring and inspecting prescription drugs. And in Massachusetts, the state actually sells alcohol through state stores.”

My opinion: I’m generally in favor of legalizing marijuana, because the 40-year-old prohibitionist model has led to drug wars that have cost tens of thousands of deaths in Mexico and Central America, with few positive results. It has cost billions, which would be much better used in drug prevention, education and rehabilitation campaigns.

But legalization of marijuana should take place amid much bigger national campaigns against drug use than what we’re seen in Uruguay. Otherwise, if we legalize drugs amid a “joyous atmosphere” of permissiveness, as Sanguinetti said, we will end up with many more drug users than today.