The group won a Supreme Court case it launched in late December last year to stop the government tearing out the tracks, successfully arguing that Parliament must pass an act to authorise the work.

But in early November, the Court of Appeal ruled against it, finding the government could proceed with the work as removing two-kilometres of track did not amount to the ‘‘closure’’ of a rail line, which would require legislation.

However, by the time the judgment was delivered, the government had already passed legislation through Parliament authorising the project.

In their joint judgment, Acting Chief Justice Margaret Beazley, Justice Robert Macfarlan and Justice Anthony Meagher noted the passing of the legislation ‘‘renders the proceedings moot except as to costs’’.

It ordered Save Our Rail to pay the government’s legal fees for both the original case and the appeal.

On Tuesday, Save Our Rail filed a notice of motion to have set aside both the costs order and judgment.

Read what the Mercury has to say here

Save Our Rail president Joan Dawson said the government should have withdrawn from the proceedings after the legislation was passed and the group had written several letters asking it to do so before the judgment was handed down.

‘‘It was a waste of court time and [legal] representatives,’’ she said.

She said the government still had not informed the group how much it would otherwise have to pay, but it was unlikely ‘‘we’d be able to afford anything near that amount’’.

Its members would not be held personally liable. 

Fairfax Media has previously revealed the costs are expected to tally to about $800,000.

Transport for NSW has spent at least $302,000 on legal fees. The Hunter Development Corporation is understood to have incurred another $500,000, which government developer UrbanGrowth has paid. The notice of motion is set down for November 30.