New South Wales Greens' MP Ian Cohen says he could become bankrupt after being ordered to pay more than $1 million in costs after losing a defamation case in the High Court yesterday.

Property developer Jerry Bennette sued Mr Cohen over comments he made during public meetings on the far north coast in 2001.

Previous court cases heard Mr Cohen defamed Mr Bennette by saying he was a thug and a bully.

Mr Cohen says he while he regrets making the comments, the case shows the difficulties faced by community activists.

"Things get said on the football field, in the pub - how sensitive are we going to be?" he said.

"It's important to recognise that we need a little bit of a buffer otherwise it becomes a situation where anything anyone says can be taken to court.

"I believe that cuts down the ability to actually represent and defend community values and attitudes and stick up for your mates, so there's a lot of downside to this general trend."