Legal arguments are emerging in the battle to stop the EU from classifying nuclear energy as environmentally friendly.
With prospects dim for changing the EU’s mind politically, Austria and Luxembourg plan to join activists in taking Brussels to court if the disputed plans go ahead.
Germany also opposes the plans, which would include nuclear reactors on a list of climate-friendly investments known as the EU taxonomy, although Chancellor Olaf Scholz's government has held back from supporting legal action.
But a lobby group called German Environmental Aid published a 25-page legal argument on Monday which accuses the European Commission of breaching the bloc’s foundational treaties.
Lawyers cited an article of the Lisbon Treaty which calls for environmental policy to be “based on the precautionary principle” – a requirement they said was breached by the hazards of radioactive waste.
This means measures to protect the planet should not only kick in when there is “imminent damage” but when risks are identified in the first place, they said.
The report said nuclear power failed the EU’s test of “doing no significant harm” to other environmental objectives, a principle written into the taxonomy regulations.
This position has previously been rejected by an EU-commissioned expert panel, which said last year that nuclear did no more harm than other energy sources if properly regulated.
Pro-nuclear countries such as France regard it as a reliable, low-carbon power source that reduces Europe’s reliance on imported fossil fuels. The EU's Internal Market Commissioner Thierry Breton supports the use of atomic energy.
Critics such as Germany and Austria highlight the risks of an accident such as Fukushima or Chernobyl and the problems of storing long-term waste.
The legal report also identified procedural issues over the EU’s use of delegated powers that lawyers claimed had expired.
“If nuclear and natural gas are really included in the taxonomy, Germany must join Austria and Luxembourg’s lawsuit,” said the lobby group’s director Sascha Mueller-Kraenner.
Unlike environmental activists, Germany does not object to the inclusion of natural gas, which it expects to rely on during the next decade as it moves away from nuclear and coal.
German Environment Minister Steffi Lemke said she would make Berlin’s opposition to nuclear plants known in EU meetings.
“Our position will be a clear no to including atomic energy in the taxonomy,” Ms Lemke told German television.
But Kevin Kuehnert, the secretary general of the ruling Social Democrats, told reporters it was “completely utopian” to think Germany could stop the EU’s plan in its tracks.
Germany was “clearly in a minority” in the 27-member bloc, he said.
Any veto would require the backing of a large majority of EU members, with nuclear sceptics unlikely to have the necessary numbers. Another possibility would be to vote the proposal down in the European Parliament.
Campaigners were further angered when the EU published its plans on New Year’s Day and allocated less than two weeks for feedback.
However, the European Commission announced on Monday that the deadline for responses would be extended until January 21 rather than expiring on Wednesday.
“The reason has been postponed by a week and the reason is basically to give a bit more time” for experts to submit their views, said European Commission spokesman Eric Mamer.