The court quashed a decision by the mining warden on Friday, declaring invalid access agreements on two Caroona properties.

It was a victory for the Brown and Alcorn families to keep BHP off their land.

Solicitor Peter Long, of Slater and Gordon at Gunnedah, said it could have repercussions for other areas, including the Hunter.

"There's no doubt that people who have had access agreements imposed upon them by the Mining Warden's Court or the Land and Environment Court may well have the right to have those access arrangements set aside [voided]," he said.

"This decision by the court will not stop mining, it's about the legalities about how an explorer gets access to properties to explore.

"If you don't go through the proper processes it does not mean it's fatal but you have to restart the process."

Mr Long said that would mean notifying all of the groups that had a stake in the properties to be explored, including the bank where the mortgage was held, if there was one.

Minewatch spokeswoman Wendy Bowman, of Camberwell, said the court's decision was "marvellous" because it was a win for landholders.

Ms Bowman said mining companies made a "complete nuisance" of themselves while exploring properties.

"They drill for coal seams and water," she said.

"It's quite annoying, they drive all over your paddocks."

Ms Bowman said Minewatch had previously come to the view it was better for owners to allow mining companies access and then negotiate how it was used.

"You can say 'you can only drive on these areas, you don't go on the farm, you have to open and shut farm gates properly, if you burn anything you have to pay or replace it, no drilling on weekends'," she said.

"It's was a better outcome than going to court because the Mining Warden's Court always gave in to the mining companies.

"This decision is good because finally land owners have had a win."

BHP declined to comment on the court's decision.