POLICE watched seven people sell drugs in Marshall Courts and Seven Oaks, two districts in south-eastern Newport News, in Virginia. They built strong cases against them. They shared that information with prosecutors. But then the police did something unusual: they sent the seven letters inviting them to police headquarters for a talk, promising that if they came they would not be arrested. Three came, and when they did they met not only police and prosecutors, but also family members, people from their communities, pastors from local churches and representatives from social-service agencies. Their neighbours and relatives told them that dealing drugs was hurting their families and communities. The police showed them the information they had gathered, and they offered the seven a choice: deal again, and we will prosecute you. Stop, and these people will help you turn your lives around.

This approach is known as drug-market intervention (DMI). It was first used in High Point, North Carolina, in 2004 and since then has been tried in more than 30 cities and counties. It is the brainchild of David Kennedy, a criminologist at John Jay College in New York, who thinks that “the most troubled communities can survive the public-health and family issues that come with even the highest levels of addiction. They can't survive the community impact that comes with overt drug markets”—by which he means markets that draw outsiders to the neighbourhood. Once these are entrenched, a range of problems follow: not just drug use and sales, but open prostitution, muggings, robberies, declining property values, and the loss of businesses and safe public spaces.

Traditional drugs policing targets both users and dealers. This poses three main problems. First, low-level dealers are eminently replaceable: arrest two and another two will quickly take their places, with little if any interruption to sales. Second, it tends to promote antagonism between the police and the mostly poor communities where drug markets are found. Arrests can seem random: only one in every 15,000 cocaine transactions, for instance, results in prison time, but those other 14,999 sales are just as illegal as that one. In some neighbourhoods, prison is the norm, or at least common, for young men. Police come to be seen as people who take sons, brothers and fathers away while the neighbourhood remains unchanged. Third, prison as a deterrent does not work. If it did, America would be the safest country on earth.

Shutting down markets, on the other hand, removes the conditions that let crime flourish. Drug sales may still occur in poor neighbourhoods, just as they do in wealthy ones, but they do so behind closed doors, and they do not have the same bad effect on community life.

And restoring community life is DMI's main objective. After the first call-in, police maintain a visible presence in the targeted neighbourhood. Recalcitrant dealers are arrested and swiftly prosecuted (two of the four no-shows in Newport News have been arrested; the other two are fugitives). Complaints by citizens are dealt with speedily, to let locals see that the police respond and want to keep the area safe. That, in turn, makes locals more likely to call the police with complaints. James Fox, chief of police in Newport News, says that without locals “acting as our eyes and ears”, DMI would not work.

It is still too early to forecast success, but on a recent weekday afternoon Marshall Courts and Seven Oaks were quiet and peaceful. Children played outside and people sat out on their porches. High Point's market was shut down eight years ago. It has still not reopened.