Even before they reached the narrow road that runs uphill into the hardscrabble neighborhood that was once one of the city's most dangerous slums, the Diadema police could see the bar shining through the sickly yellow lamplights.
It was 11:50 p.m. and a gathering of men in front of a brightly lit shop front could only mean one thing: alcohol.
The 14 police and inspectors parked their cars in front of Lede de Souza's ramshackle bar-cum-front room and quietly went to work.
"Do you know it's illegal to serve alcohol after 11 p.m.?" an inspector asked. "Yes," Mr. de Souza replied with a sheepish smile, "but we've been renovating here and we were just having a few beers while we clear out the rubble."
The officers were polite but stern. Their message was clear: Serving alcohol would not be tolerated. Less than 10 minutes later, the lights were out, the store shutter was down, and de Souza was off to bed with an official warning.
The long arm of the law has been preaching - and enforcing - prohibition in Diadema for four years now. Under a bold and controversial bill passed in 2002 to combat the alcohol-fueled bloodshed that made this industrial city one of the most violent in Brazil, authorities banned the serving of liquor after 11 p.m. in almost all the city's 4,800 bars and restaurants.
Those caught flouting the law are, like de Souza, first warned, then fined 125 reais (about $60). A second fine doubles the amount. Finally, if they persist, their places are closed down.
The effect has been stunning.
"The number of murders fell by 47.4 percent in Diadema between 2002 and 2005," said Regina Miki, the city's social services secretary. "The number of road accidents fell by 30 percent. The number of assaults against women fell by 55 percent. And the number of alcohol-related hospital admissions fell by 80 percent.
"It's all because of this law," he adds.
The law, and the subsequent reduction in violence, has been such a success that municipalities across Brazil are adopting similar measures. At least 120 towns and cities have restricted bars' hours, and the federal government is offering authorities who implement the measures additional funds for law enforcement.
"The other municipalities look at Diadema and see how the scope has changed," says Cristina Villanova, the coordinator of law-enforcement prevention strategies at the Ministry of Justice. "They are no longer basing their programs on just arresting people but on stopping people from getting involved in criminal activity before it happens."
One in 10 deaths are alcohol-related
Experts say the measures are long overdue given the intense damage caused by alcohol. In Brazil, 17 percent of men suffer from alcohol-related problems or dependence, and more than 1 in 10 deaths are alcohol-related. That is 2-1/2 times the world average, according to the Brazilian Psychiatric Association.
With little federal control over alcohol sales or consumption, closing bars in troubled areas is a logical and efficacious way to cut alcohol-related problems, says Ronaldo Laranjeira, a Sao Paulo doctor who led a joint Brazilian-US team studying murder rates in Diadema following the ban.
"From a public health point of view, it is cheap and it has a great impact," Dr. Laranjeira says. "The overall murder rate in Brazil is so high that given the relationship between alcohol and violence, the impact of these new drinking-hours restrictions has considerable implications for public health, and shows that alcohol-related violence can be tackled."
The idea came from Jose de Filippi Jr., the mayor who took office in 2001. The city, a rough, densely packed sprawl of almost 400,000 people on Sao Paulo's southern outskirts, was notorious for its violence. After sending researchers to study the sources of the trouble, Filippi discovered why.
The majority of crimes - and 60 percent of all homicides - took place at night in and around the city's bars and restaurants. Filippi canvassed public opinion over a possible alcohol ban and found that most residents would be supportive. In March 2002, the city council passed a bill prohibiting the sale of alcohol between the hours of 11 p.m. and 6 a.m.
The law gives special dispensation to establishments that are soundproofed, far from residential or violent areas, and have their own security guards. So far, 30 have been granted special licenses.
Initially, few people believed the ban would work. Miki acknowledges that many Brazilian laws often go unenforced. Diadema took care to ensure this one would not be rendered ineffective by the corruption and poor organization that blight many of the country's institutions.
When the four cars go out on patrol each night, only the team leader knows the route they will take. The military and local police and inspectors all ride together, making it hard to corrupt one without the knowledge or cooperation of the others. Police regularly change their set plans if a local hotline receives information that bars are flouting the law.
Even those measures, however, did not convince skeptical residents and bar owners unaccustomed to such stringent controls. It was only after officials shut down the City Club, one of Diadema's best-known nightclubs, that they got the message.
"People thought it was just another law they wouldn't need to obey," Miki says during a late-night interview shortly before heading out on patrol. "But in two days they could see we weren't joking."
Since then, Diadema's other establishments have closely obeyed the law - and only 15 have been closed. Businesses once scared off by the city's violent past are now returning. For 20 consecutive months, Diadema led the state in the number of jobs created, and is quickly gaining a reputation as a model of abstinence and urban renewal.
"Look at the city," Miki says as she surveys the deserted streets through the car window. "It's quiet. This is just how I like it. No murders."