In December 2011, the Dutch government asked virologist Ron Fouchier to do something unheard of. Fouchier had shown how a few mutations could make the H5N1 bird flu virus transmissible among ferrets, but before he could send a second draft of his paper to Science, the government required him to apply for an export license. Fouchier was outraged. But in a 20 September ruling, a district court in Haarlem, the Netherlands, said that government officials had correctly interpreted a 2009 E.U. regulation when they asked Fouchier to apply for the license. Now, it appears that far from being an anomaly, the episode has set a precedent, raising complex questions about how the Netherlands will regulate sensitive biomedical research in the future.