Adani's lawyer Liam Kelly says Galilee Blockade leader Ben Pennings had urged people to leak confidential project information via its "dob in an Adani contractor" website.

"There are millions of dollars in increased costs," Mr Kelly told the Brisbane Supreme Court on Friday of the Carmichael mine and rail project.

He said security costs had "dramatically" increased in response to Mr Pennings' activities and "tier one" contractors had been "scared off".

"The smaller contractors who take on the work .... don't have the experience and wherewithal of someone like (construction group) Downer," he said.

"This has already caused problems."

Mr Kelly said Mr Pennings had also threatened to disrupt other contractors' business activities unless they got "out of bed" with Adani.

The mining giant has applied to the court to stop the father of four damaging its "legal and legitimate commercial interests".

It wants Mr Pennings to pull down the Galilee Blockade website and social media posts targeting contractors.

It also wants him to stop encouraging people to leak business information.

"What he is doing is unlawful. He is asking for people to break their contracts and provide confidential information," Mr Kelly said.

"There is no contrition or remorse for his behaviour. He is a true believer in his cause."

Mr Pennings, who represented himself in court, said Adani was attempting to stifle a peaceful protest.

He said other courts had already dealt with similar claims by Adani about his alleged possession of confidential information and protest activities.

"They've been unable to discern what information Adani says I hold or have obtained," he said.

"The judges weren't satisfied that it had been provided in breach of any contractual or equitable obligations."

Outside of court, the father of four said he was working to protect the environment and his family.

"Adani's attack dog legal strategy could ultimately bankrupt my family, making us sell our home so a billionaire gets richer," he said.

Justice Glenn Martin reserved his decision.

Australian Associated Press