Australian Greens Leader Senator Bob Brown says Gunns' pay-off to the last 4 defenders in the notorious Gunns-20 case is a total back down and utter defeat for the litigants.

"Gunns has lost more than $1 million, and a much greater amount in damage to its reputation, by suing twenty environmentalists defending Tasmania's wild forests," said Senator Brown.

"This is ‘WE WERE WRONG' writ large by Gunns.

"Governments should legislate to prevent powerful, rich corporations like Gunns taking huge punitive actions like this to silence opponents," Senator Brown said.