Government plans to press ahead with the HS2 national high-speed rail project will be challenged today in the highest court in the land.
The HS2 Action Alliance (HS2AA) and local councils along the route failed in a Court of Appeal bid to force a further assessment of the scheme as a whole and are now asking the Supreme Court to intervene.
The man due to spearhead the estimated £50 billion project defended it yesterday and told MPs it had never just been about speed.
Sir David Higgins, who is soon to take over as chairman of HS2 Ltd, said it was also about improving capacity and about connecting major cities.
Currently chief executive of Network Rail (NR), Sir David told the House of Commons Transport Committee that he had been keen to get involved with HS2 because he feared the project was becoming "a political football" and it was "too important" to be so regarded.
Although they lost in the appeal court, HS2AA 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 gauge 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 the public importance of the case, the appeal court gave the objectors permission to appeal on the SEA issue.
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 say 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, including 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."
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.
London Mayor Boris Johnson has predicted more than £70 billion.
A Department for Transport spokesman said: "HS2 is absolutely vital for this country if we are to meet the urgent capacity needs we face.
"Attempts to obstruct HS2 have already been firmly rejected by two courts.
"The Government will continue to defend any challenge in the Supreme Court, but strongly believes Parliament is the right place to debate the merits of HS2, not the courts."
Hilary Wharf, director, HS2AA, said: "It's is a sad day when hard working tax-payers have to take the Government to the highest court in the land to ensure that it protects irreplaceable environments for future generations.
"The very fact that we have been given the right to appeal to the Supreme Court and seven judges are sitting shows the vital importance of this case, not just for the right decisions to be made around HS2, but for future national infrastructure projects."
HS2AA says a thousand people donated £50 each over five days to fund the Supreme Court action.
It warns HS2 would have "a hugely damaging" environmental impact up and down the line, threatening 350 unique wildlife habitats, 30 river corridors and 24 sites of Special Scientific Interest.
"Phase One alone would bring devastation to the Meridien Gap (the greenbelt separating Coventry from Birmingham), the Leam Valley in Warwickshire and the Chilterns Area of Outstanding Natural Beauty, as well as destroying 50 irreplaceable ancient woodlands.
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 recently cast doubt on the scheme.
But Prime Minister David Cameron has said HS2 is essential if Britain is 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.
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.
Among the 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 is calling for the Government 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.