Austin Smith and others argue in favour of patenting technologies derived from human embryonic stem cells (Nature 472, 418; 2011), a case still pending with the European Court of Justice. But there is more at stake than European commercial interests. In 1998, agreement was reached in Europe under Directive 98/44 not to recognize patents involving the use of human embryos for commercial purposes (R. Hipp and P. Liese Nature 474, 36; 2011). The court must decide whether the use of these cells \u2018necessitates the prior destruction of human embryos or their use as base material\u2019, as the advocategeneral, Yves Bot, has argued (see go.nature.com/gsap8n). If so, such use would seem to fall beyond the scope of what is legally patentable. Smi...