By Tom Parmenter, Sky News Correspondent
Campaigners have vowed to fight on after the Court of Appeal rejected their latest challenges to the Government's HS2 high-speed rail project.
Objectors including 15 councils and residents' associations along the route had wanted judges to order further assessment of the entire scheme.
But their plea was dismissed on all grounds - although they were granted the right of a final appeal to the Supreme Court, the highest court in the land.
The Department for Transport said the ruling would allow them to press on with the project.
High Speed Rail minister Simon Burns said: "This is the second time in four months a court has rejected attempts to derail HS2.
"I urge opponents not to waste any more taxpayers' money on expensive litigation and instead work with us on making HS2 the very best it can be."
However, campaigners declared they would battle on to ensure the Government does not "duck its environmental responsibilities".
Hilary Wharf, director of the HS2 Action Alliance (HS2AA), said: "We are confident that our position is a strong one and we are pleased that the Court has allowed our appeal to the Supreme Court.
Lord Mandelson has raised doubts about HS2"It's concerning however that we have to go to the highest court in the land to make the Government give the environment the respect it deserves."
The scheme is the country's largest infrastructure project for a generation and the largest single rail project since the 19th century.
The proposed route would run from London to Birmingham before splitting into lines that run through Manchester and Leeds.
The estimated cost of the scheme has recently risen from £33bn to £42bn, although critics put the figure at closer to £60bn.
They also argue it will cause environmental damage, the loss of homes and disruption to many communities.
Former Labour cabinet minister Lord Mandelson and ex-transport secretary Alistair Darling are among those to have cast doubt on it in recent weeks.
But on Tuesday, David Cameron reiterated its importance to securing Britain's position in his much-trumpeted "global race".
David Elwin QC, appearing for the HS2AA, argued that the scheme needed a strategic environment assessment (SEA) before it could proceed.
He claimed the Government had broken a European directive requiring an SEA and called for the High Court's ruling in March to be overruled.
Nine areas of legal challenge were brought to the High Court but the only one to succeed related to the property compensation consultation, which is now being re-run.
Despite the latest failure, campaigners drew comfort from a split in the three-judge panel on whether an SEA should have been carried out.
Lord Dyson, the Master of the Rolls, and Lord justice Richards, backed the Government but Lord Justice Sullivan disagreed.
Councillor Martin Tett, chairman of the 51m alliance and leader of Buckinghamshire County Council, expressed disappointment at the latest ruling.
He said: "This is another example of the Department for Transport and HS2 Ltd riding roughshod over public opinion, ploughing ahead regardless of what local communities want and ignoring the environmental merits of the alternatives.
"We have evidence that our alternative to HS2 would provide all of the capacity required, far more quickly, at a fraction of the cost and would be less damaging to the environment."
Construction on phase one of the route between London and Birmingham is due to start in 2017.