“I’m not crazy. I know they can’t predict earthquakes,” the Italian public prosecutor Fabio Picuti told Nature last year. He was speaking as the manslaughter trial began in the ruined town of L’Aquila of six scientists and one government official for their alleged role in the deaths of 309 people in the quake of April 2009 (see Nature 477, 264–269; 2011). On Monday evening, the seven were found guilty and sentenced to six years in prison (see Naturehttp://doi.org/jkp;2012). The verdict is perverse and the sentence ludicrous. Already some scientists have responded with warnings about the chilling effect on their ability to serve in public risk assessments.

Even Picuti was surprised. He had requested a prison term of four years. “We’ll have to read the judge’s motivations to understand why,” he said. Under Italian law, judge Marco Billi has up to three months to reveal his reasoning.

Despite the way the verdict has been portrayed in the media as an attack on science, it is important to note that the seven were not on trial for failing to predict the earthquake. As members of an official risk commission, they had all participated in a meeting held in L’Aquila on 31 March 2009, during which they were asked to assess the risk of a major earthquake in view of the many tremors that had hit the city in the previous months, and responded by saying that the earthquake risk was clearly raised but that it was not possible to offer a detailed prediction. The meeting was unusually quick, and was followed by a press conference at which the Civil Protection Department and local authorities reassured the population, stating that minor shocks did not increase the risk of a major one.

According to the prosecutor, such reassurances led 29 victims who would otherwise have left L’Aquila in the following days to change their minds and decide to stay; they died when their homes collapsed. The prosecutor thus reasoned that the “inadequate” risk assessment of the expert panel led to scientifically incorrect messages being given to the public, which contributed to a higher death count.

The seven — Bernardo De Bernardinis, Enzo Boschi, Giulio Selvaggi, Franco Barberi, Claudio Eva, Mauro Dolce and Gian Michele Calvi — are appealing against the verdict. They will remain free until the appeals process is finished, which could take years.

That provides an opportunity. There will be time enough to ponder the wider implications of the verdict, but for now all efforts should be channelled into protest, both at the severity of the sentence and at scientists being criminalized for the way their opinions were communicated. Science has little political clout in Italy and the trial proceeded in an absence of informed public debate that would have been unthinkable in most European countries or in the United States. Billi should promptly explain his decision, and the scientific community should promptly challenge it.