The House of Lords is being asked to consider whether the legal battle over night flights into Heathrow should end where it stands with July's Court of Appeal ruling in favour of the Government's backing for upgrading the level of flights.
But a top environmental lawyer who is closely involved in the action has accused the Court of Appeal of allowing the Government "to have its cake and eat it".
Cambridge-based Richard Buxton, who masterminded the case for the local authorities, said the Court of Appeal ruling will add a new dimension to the Terminal Five inquiry (T5) when it considers noise levels, probably in May next year.
The case involves a long-running battle between six local authorities - the Lon don boroughs of Richmond, Hillingdon and Hounslow, the Royal Borough of Windsor and Maidenhead, Slough Borough Council and Surrey County Council - and the Government.
The July decision came in the wake of three earlier actions in which the same authorities won important rulings against the Government.
In 1993 an application for judicial review of the Government's night flying restrictions scheme resulted in a judgment from Mr Justice Laws which effectively cut the potential maximum number of night flights from 24,000 to 6,000.
In 1994 Mr Justice Latham upheld a claim by the authorities that they had been "materially misled" when the Government said a new scheme would not increase noise levels. He ordered reconsultation.
And last year, Mr Justice Sedley held that the the Government had been acting in "a devious and deeply unattractive way" over the reconsultation.
In the end it made what Buxton calls an "extremely grudging admission" that policy had changed "a bit".
But when the case returned to the High Court for a fourth hearing in March this year, Mr Justice Jowitt effectively held that the Government no longer had a policy of not allowing the worsening of noise at night or improving it, and that therefore it was lawful for noise levels to be increased. That decision won the support of the Appeal Court.
"The Court of Appeal has allowed the Government to get away with having its cake and eating it," said Buxton.
"Our case has rested on the inadequacy of consultation and lack of reasons for the way the scheme makes the noise climate worse. The Court of Appeal acknowledged that the scheme impinged on people's human right to have a good night's sleep, but the consultation and reasoning satisfied the rules entitling governments to balance these rights against the economic interest of the country.
"It also held that there is a difference between the need for a decision maker to have regard for policy in situations like this, compared with planning decisions where there is, as Lord Justice Brook put it, a 'highly developed statutory framework'. He said it is good enough for the minister simply to 'identify his policy objectives'."
Buxton added: "We are in the extraordinary position that the courts have now found that the Government must have changed its policy so as to allow noise to get worse at night, but it has given evidence at T5 that its policy remains to improve the noise climate, in line with its 1985 Airports White Paper.
"Although there are interesting legal arguments about consultation and reasoning, we think the Government has said so little because it made an awful mistake with this scheme and just hates to admit it."