It is difficult to over-emphasise the potential for stem cell research to revolutionise medicine. Already, after barely more than a decade, scientists look forward to treatments for blindness, for spinal cord injuries, for degenerative conditions such as Parkinson's. Further in the future are possible therapies for everything from diabetes to cancer to arthritis.

With so much to gain, every possible effort should be made to speed the necessary research. Elsewhere in the world, that may be so. But Europe is facing what one expert has called "a Dark Age of stem cell research" after yesterday's legal ruling that no invention based on work using cells from human embryos can be patented.

The catastrophe now threatening investment in the European biotechnology industry began with a legal action from Greenpeace in Germany, in protest against what the group claims amounts to the commercial exploitation of human embryos. At the root of the criticism is a concern that neither scientists nor their employers be allowed to "patent life". Such emotive rhetoric may appear superficially convincing, and also chimes with religiously inspired opposition to the use of embryo tissue. But the analysis is simplistic and the price of such moral objections is too high.

Strong intellectual property rights are central to research and development of all types. Without patents, such activities are all but impossible to fund beyond the initial research stage. The likely result? An unforgivable delay in the development of treatments for disabling and life-threatening conditions.

The only ray of light is the hope either that skilful lawyers may be able to draft around the ruling, or that much-needed patents can be obtained in other jurisdictions, such as the US and Asia. Neither solution is ideal, either for the swift development of new medicines or for the future of European biotech.

Stem cells arguably promise the most radical medical advance since the discovery of penicillin. The ethical issues the research raises – and there are many – must be dealt with by careful regulation and oversight. To stymie progress with unthinking patent laws is indefensible.