In October, demonstrators protested against the use of monkeys in research at the Max Planck Institute in Tübingen. Credit: Thomas Niedermüller/dpa/Corbis

German police seized documents in a raid on Tuesday on the Max Planck Institute for Biological Cybernetics in Tübingen, as part of an investigation into alleged violations of animal-protection laws.

Science pours in from Rosetta comet mission GM microbes created that can’t escape the lab Crunch time for pet theory on dark matter

The investigation was launched last year after a video shot by an animal-rights activist who infiltrated the institute was broadcast on television in September. An independent investigation carried out by the Max Planck Society found no systematic problems, and this month the state government of Baden-Württemberg said that, following its own investigations, it saw no reason to revoke any animal licences.

A spokesperson for the Max Planck Society in Munich, who asked not to be named, told Nature that activists were carrying out an unjustified campaign against the institute, where some scientists use monkeys in their research on how the brain works.

“There is an agreed consensus within society about how much research can be done with animals and in what conditions,” the spokesperson said, adding that society wants researchers to tackle diseases such as dementia — but that this cannot be done without using animals. “The work is carried out correctly in Tübingen — we have nothing to hide.”

Friedrich Mülln, head of the Augsburg-based activist group SOKO Tierschutz — which last year pledged to continue actions against the institute until it stopped its monkey research — says that the Max Planck Society is lying about the animals' treatment, and that the Tübingen institute is a “black mark on an otherwise admirable organization”. He added that his group is working closely with police.

“We are seeing this type of pressure on scientists all around Europe and we are worried,” says Monica Di Luca at the University of Milan, Italy, who is president of the Federation of European Neuroscience Societies in Brussels. “It is threatening important fundamental research that needs to be done to combat diseases and disability.”