A Canberra court has dismissed an appeal by landholders fighting for compensation after they were burnt out by the 2003 Canberra bushfire disaster.
But Brindabella landowner Wayne West would not rule out a High Court challenge.
Speaking outside court after the judgment, Mr West said he had been "devastated" by the decision.
Mr West said a High Court bid would be considered, but his legal team would need to read the decision in full first.
"We will read the decision … and look at our future direction," he said.
"We'll be looking at our options, [it] will take probably another week to read [today's] decision … to see what future direction we can take."
Mr West also thanked all those who had provided support since 2003.
Friday's decision closes another chapter in the marathon 2003 bushfire lawsuit – the largest single piece of civil litigation in the territory's history.
The inferno ripped through Canberra's south-western suburbs on January 18, 2003, killing four people, injuring 435 injured, and destroying 487 homes and 23 commercial and government buildings.
In December, 2012, an ACT Supreme Court judge found NSW had adopted an "inadequate and defective strategy" to fight the fires.
But former Chief Justice Terence Higgins found NSW was not legally liable to pay compensation.
The judge found faults with the fire authorities' strategy, including the decision not to fight the McIntyre's Hut fire at Baldy Range at first light on January 9, and the failure to backburn along the Goodradigbee River.
But former Justice Higgins found that, although NSW would have been liable at common law, it was protected from liability by section 128 of the Rural Fires Act.
The case then went to ACT Court of Appeal, where both the landholders and NSW challenged the decision.
The appeal was heard over nine days in May and June and the decision was reserved.
The Court of Appeal on Friday found that NSW could not be sued because the Rural Fires Act protected it from liability.
Chief Justice Helen Murrell, in handing down the decision on Friday, read a short summary to the court.
"All members of the court held that NSW had proved that it was protected from civil liability by section 128 of the Rural Fires Act, which provides a complete defence from liability for matters or things done or omitted to be done by a 'protected person or body' 'for the purpose of executing any provision … of (the) Act or any other Act'.
"For this reason alone, the appeals had to be dismissed."
The court also found that NSW did not owe land holders or Canberrans a duty of care.
"If the first duty of care was owed, the evidence did not establish any lack of reasonable care by the incident controllers in not directly attacking the spot fire on the Baldy Range on the morning after the fires ignited or in not clearing and back-burning vegetation along the length of the Goodradigbee River," Justice Murrell said.
"[The judges] also held that the evidence did not establish that the alleged breaches of the first duty of care caused the harm which the plaintiffs suffered.
"In respect of the second duty of care, all members of the court held that if any such duty to warn the residents of Canberra existed, the evidence did not establish that the commissioner of the Rural Fire Service had acted in breach of that duty."
Correction: An earlier version of this story said the cross-appeal by NSW had been thrown out, too. This is not the case. The judges found NSW did not breach its duty of care.