A court in Australia is considering whether to award millions of dollars in damages against environmental NGOs in a case that could have implications in the UK.
The NGOs are accused of "interfering with the trade and business" of a Tasmanian forestry company called Gunns.
Campaigners say the legal action could herald the start of a corporate assault on attempts by civil society organisations to hold companies to account.
"This is going back to the 19th century, when freedom of contract overrode public interest and the right of people to speak out," said Stephen Lloyd, partner at charity specialist solicitors Bates, Wells and Braithwaite.
He added that the Serious Organised Crime and Police Act, introduced in the UK last year, could help companies to follow Gunns' example. The Act allows companies to take out civil injunctions to stop "harassment".
"This could cover urging individuals to carry out consumer boycotts," said Lloyd.
Gunns claims a group of activists damaged its profits by urging Japanese paper companies to buy woodchip from plantations and not old-growth forests.
The company also claims it lost "prestige" after being withdrawn from the shortlist for an environmental prize following protests about its logging activities.
Friends of the Earth International and Greenpeace have condemned the lawsuit as an "assault on democracy and free speech".
Greg Ogle, legal co-ordinator with the Wilderness Society, said there is a long history of campaigns that disrupt business.
"Presumably, those with the British salt monopoly could have sued Gandhi for his salt march and South African businesses may have had a claim against anti-apartheid activists," he said in a discussion paper.