Members of the public have the right to wild camp in Dartmoor National Park, the Court of Appeal has ruled.

In January, a High Court judge ruled a nearly 40-year-old piece of legislation did not give people the right to pitch tents overnight on Dartmoor Commons without landowners’ permission.

Alexander and Diana Darwall brought the successful legal challenge against the Dartmoor National Park Authority (DNPA), claiming some campers cause problems to livestock and the environment.

Earlier this month, the DNPA asked appeal judges to overturn Sir Julian Flaux’s decision, arguing he had the wrong interpretation of a 1985 law over rights of access to Dartmoor Commons.

In a ruling on Monday, Sir Geoffrey Vos, Lord Justice Underhill and Lord Justice Newey granted the appeal, finding that the law “confers on members of the public the right to rest or sleep on the Dartmoor Commons, whether by day or night and whether in a tent or otherwise” as long as byelaws are followed.

Sir Geoffrey said the “critical question” was whether wild camping could be considered a form of “open-air recreation”, finding it was.

He said: “The fact that a tent is closed rather than open cannot convert the wild camping from being an open-air recreation into not being one.

“In my judgment, that walker is still resting by sleeping and undertaking an essential part of the recreation.”

Lord Justice Underhill, who agreed with Sir Geoffrey, added the byelaws “provide a workable structure whereby a proper balance can be preserved between the rights of those accessing the commons and the rights of the owners of the land and others”.

He added: “Many people take pleasure in the experience of sleeping in a tent in open country, typically, though not invariably, as part of a wider experience of walking across country, and perhaps engaging in other open-air recreations such as birdwatching, during the day.

“It is a perfectly natural use of language to describe that as a recreation, and also as occurring in the open air notwithstanding that while the camper is actually in the tent the outside air will be to some extent excluded.”

Sir Julian had previously found that the meaning of the legislation was “clear and unambiguous” in that it conferred a “right to roam” which did not include “a right to wild camp without permission”.

His now-overturned judgment was labelled a “huge step backward” by campaigners, who said there was a “long-established precedent” of wild camping in the national park in Devon.

The DNPA’s chairwoman, Pamela Woods, said the organisation was “delighted” with Monday’s appeal decision, with DNPA’s chief executive Kevin Bishop saying the ruling is “a re-affirmation of the right to backpack camp on Dartmoor and secures that right for today and future generations”.

He added: “Our sincere hope is that this judgment means we can now move forward, in partnership, with a focus on making sure Dartmoor remains a special place for all to enjoy.”

The ruling was also welcomed by the Open Spaces Society, which intervened in the case.

Its general secretary Kate Ashbrook said: “This is an excellent outcome. We are relieved that the judges ruled unanimously and conclusively that open-air recreation includes backpack camping on the commons.”

She added: “Following this judgment, Dartmoor remains one of only a handful of places in England where there is a right to backpack camping without the landowner’s permission.

“We should like to see that right extended and we shall campaign with other organisations to achieve this.”

Dartmoor National Park, designated in 1951, covers a 368-square mile area that features “commons” – areas of unenclosed privately owned moorland where locals can put livestock.

The DNPA previously said backpack campers can access nearly 52,000 acres of common land across the national park and can stay overnight under a new “permissive system” as long as they follow a code of conduct.