Berlin - Germany's extension of the legal lifetimes of 17 nuclear power plants passed into law Wednesday, with President Christian Wulff assenting to the legislation in Berlin.
The 12-year deferment of the sunset date for nuclear power, a key policy plank of Chancellor Angela Merkel's government, still faces challenges by anti-nuclear opponents in the courts.
Wulff's office confirmed a signature had been put on the bill, the final move after its passage by the lower chamber of parliament.
Several German states ruled by the opposition Social Democratic Party (SPD) have said they will challenge the bill in the constitutional court.
The SPD wants the old closure dates left unchanged and is angry that the legislation by-passed the upper chamber of parliament, where Merkel does not command a majority. Anti-nuclear activists charge Merkel has breached a social compact over the divisive issue.
Germany faced its fiercest demonstrations for years November 5-8 as the anti-nuclear movement tried to block rail lines and roads to hinder a shipment of nuclear waste to a storage warehouse south of Hamburg.
Wulff's signature indicated he did not agree with warnings that the legislation might have been passed unconstitutionally.
A statement said careful analysis revealed no legal obstacles to presidential assent. The largely ceremonial president has the power to halt legislation if it is unconstitutional.
Under previous legislation, which allows power generating companies set quotas of power, the plants would have all been deactivated by 2022. With an average extra 12 years per plant, the last one will now stay in operation till 2036.
The legislative package includes a new tax on the power companies, with the proceeds to be used to encourage solar and wind power.