The battle over the third runway at Heathrow airport is far from finished, by Richard Garlick

But we are still at least three years away from a grant of planning permission, according to experts. Many potential pitfalls lie in wait. First is the parliamentary vote, which is due before 11 July. Ministers can expect trenchant criticism of the NPS’ approach to mitigating air quality and noise impacts of the third runway, which does not meet the demands made by the House of Commons transport select committee. They will also anticipate complaints that the statement does not place tight enough requirements on Heathrow to offer more domestic connections, another committee recommendation that was not adopted.

If the NPS clears the parliamentary hurdle, legal difficulties are likely to await, say commentators. National Infrastructure Planning Association board chairman Angus Walker predicts a challenge to the government’s designation of the NPS, which is due in July. Assuming that is warded off, a Development Consent Order application will then have to be submitted, under the process for determining applications for Nationally Significant Infrastructure Projects. Given favourable circumstances, experts say such a consent could be given in 2021. But that too could face a legal challenge.

So the battle over the third runway is far from over. But the parliamentary debates will at least provide an opportunity to proof the NPS against one recently emerged legal threat that is troubling local planning authorities. The threat comes from a recent European Court of Justice ruling (see News Analysis p06) on how the impact of a plan or proposed development on protected habitats should be assessed, the full implications of which are only just becoming clear.

Essentially, the judgment says that decision-makers should not decide that a detailed habitats regulations assessment of the impact of the proposal is unnecessary on the basis of promised mitigation measures. Last month, the Planning Inspectorate wrote to its inspectors to say that councils with local plans at examination stage may have to carry out fresh consultations in order to take the judgment into account. Central Bedfordshire Council has already been told that its recently submitted local plan document may not be "legally compliant" in light of the ruling.

It seems that the airports NPS also runs counter to the European Court judgment. The NPS tells applicants that they should include details of any measures that are proposed to minimise or avoid any likely significant effects on a protected site, on the basis that they might assist the secretary of state in concluding that a full habitats regulations assessment is not required. In fact, to accord with the new court ruling, the NPS should be telling applicants that the mitigation measures will not be a factor in the decision. It is a problem that can be easily rectified, but illustrates just how wide-reaching an impact the court verdict could have.

Richard Garlick, editor, Planning // richard.garlick@haymarket.com