Objectors remained defiant today after the Court of Appeal rejected their latest challenges to Government plans to go ahead with the HS2 national high-speed rail project.
Fifteen councils and many other objectors, including residents' associations along the route, had asked the appeal judges to order further assessment of the scheme as a whole.
All grounds of challenge were dismissed, but anti-HS2 campaigners drew comfort from a split in the three-judge court on the key question of whether a full strategic environmental assessment (SEA) should have been carried out to assess the impact of both HS2 and its alternatives.
Two of the judges - Lord Dyson, the Master of the Rolls, and Lord Justice Richards - supported the Department of Transport's contention that an SEA under a European Directive was not required.
But Lord Justice Sullivan disagreed and added the warning: "If, as I have concluded, an SEA is required and there has not been substantial compliance with the SEA Directive, it would be difficult to think of a more egregious breach of the Directive given the scale of the HS2 project and the likely extent of its effects on the environment."
Because of its public importance, the appeal court gave the objectors permission to bring a further appeal on the SEA issue before the Supreme Court, the highest court in the land.
They also gave permission for a further appeal over a second EU Directive - the Environmental Impact Assessment Directive (EIAD).
Buckinghamshire County Council and other local authorities unsuccessfully contended that the parliamentary hybrid Bill procedure being used by the Transport Secretary to seek development consent for the two phases of HS2 was not capable of achieving the objectives of the EIAD - particularly ensuring full public participation in the decision-making procedures.
David Elvin QC argued on behalf of the objectors: "The level of parliamentary scrutiny in a proposed hybrid Bill would not meet the standard of scrutiny required by European law, given the all-party support for HS2 and the fact there would be a whipped vote".
Hilary Wharf, director of HS2AA, welcomed the court's decision to allow the Supreme Court to give a final decision on the scheme.
She said: "It's a positive move and we are confident that, at the end of the day, the Government are going to have to do a strategic environmental assessment and take their environmental obligations seriously."
But High Speed Rail Minister Simon Burns said: "By dismissing all seven grounds of appeal and declining to refer the case to Europe, this is the second time in four months a court has rejected attempts to derail HS2.
"Parliament is the right place to debate the merits of HS2, not the law courts, and we will introduce the hybrid Bill for Phase One before the year is out.
"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.
"We continue to move forward with the crucial business of getting the scheme ready for construction in 2017 and delivering enormous benefits for the country."
Objectors say it will cost far too much to get HS2, as currently envisaged, up and running from London to Birmingham, Manchester and Leeds. They estimate £58 billion and rising.
The official all-contingency cost of the project has recently climbed from £33 billion to £42.6 billion.
Former Labour Cabinet minister Lord Mandelson, ex-chancellor and former transport secretary Alistair Darling, and ITV chairman and former Tory MP Archie Norman have all cast doubt on the scheme in recent weeks.
But yesterday Prime Minister David Cameron reiterated HS2's importance, saying it was essential if Britain was to be a winner in the global race.
The project is being seen as the country's largest infrastructure project for a generation and the largest single rail project since the 19th century.
The objectors say it will cause an unacceptable level of environmental damage, loss of homes and disruption to many communities - without the public having had a fair hearing and a chance to suggest reasonable, cheaper alternatives.
The court heard that Phase One of HS2 involves creating a high-speed link between London and Birmingham, allowing through trains to run on to the West Coast main line to service cities further north.
Proposals include a new interchange station at Old Oak Common in west London, with a connection to Crossrail, the Heathrow Express, Great Western main line and local public transport, and a direct link to the Channel Tunnel.
Phase Two proposes to extend the project from the West Midlands further north to Manchester on the western fork and to Leeds on the eastern fork.
Today's appeal was against a High Court ruling which dismissed eight of the original nine areas of legal challenge.
Only one succeeded in the High Court and concerned the way in which the property compensation consultation for HS2 was carried out. The consultation is now being re-run.
HS2AA has raised £100,000 to challenge the SEA decision.
Among the 15 local authorities involved in the appeal is Camden Council in London, which says it represents the most affected area along the entire HS2 route and fears a "decade of blight".
It has issued a stark warning that the Government needs to go back to the drawing board in order to properly understand and respond to the impact of high-speed rail on local people, businesses and commuters.
Martin Tett, chairman of the 51m alliance and leader of Buckinghamshire County Council, said after today's ruling: "Yes, we are disappointed with the result.
"On four grounds brought to the Court of Appeal by the local authorities, the appeal judges found against us on the technicality that in theory Parliament is not bound by any decision of the Government and could chose to reject or amend the project.
"Most significantly, there was a split decision by the three judges on the first ground that a full strategic environmental assessment (SEA) should have been carried out to assess the effect on the environment of both HS2 and its alternatives.
"Lord Justice Sullivan gives a very strong steer that HS2 Ltd has failed both in its obligation to fully assess the environmental implications of the project and, vitally, to assess these against the alternative we have put forward.
"His comments in his judgment are damning of the Department for Transport's approach.
"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."