Seven Supreme Court judges today rejected claims by anti-HS2 campaigners that the government was "cutting corners" to push through the project.
Objectors appealed to the court that the proposals breached European environment laws.
But the judges unanimously ruled there was "no reason" why MPs would not be able to examine and debate the plan in accordance with the relevant laws.
They also said there was no need to refer the case to the European courts.
Transport Minister, Baroness Susan Kramer, welcomed the decision.
The government's handling of the project has been vindicated by the highest court in the land.
We will now continue to press ahead with the delivery of HS2.
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Billie Whitelaw, who starred in films including The Omen, has died aged 82.