In a call that is likely to embolden protest groups, the Federal Government has been urged to change environment laws so that legal costs pose less of a barrier to legitimate public challenges to controversial projects.

Allan Hawke was hired to review environment laws for the Environment Minister, Peter Garrett, and said the threat of paying costs was ''one of the most significant barriers to public-interest litigation''.

Among recommendations to improve public access to the courts, Dr Hawke said those seeking an injunction should not have to first prove they can cover the costs of the delays their action may cause.

This concept, known as ''undertakings as to damages'', has been in place since the Howard government altered the laws in 2006.

Injunctions can cost millions of dollars a day on large projects as hired equipment lies idle. Those seeking lengthy injunctions often have to offer a virtual bond before having their request heard.

Dr Hawke said the reasoning for such undertakings was ''unconvincing'', and he called for change.

He also called for the abolition of another ''major obstacle'' faced by community groups - known as ''security for costs'' - which forces a plaintiff to prove they can cover the legal bills of their opponents before starting a trial.

Environmentalists have long accused the Government of using the threat of costs to silence grassroots protesters.

A Federal Court justice, Tony North, accused state and federal governments last year of seeking ''scalps to hang on the fence'' after costs were sought from an unsuccessful community group with less than $3000 in the bank.

Jenny Warfe, an anti-dredging campaigner, led the group Blue Wedges to several unsuccessful court challenges against dredging in Port Phillip Bay.

She said she was ''pleasantly surprised'' by Dr Hawke's calls and hoped that Mr Garrett would adopt them.

John Wright, who led anti-desalination campaigners in their unsuccessful Federal Court challenge against the approval of the Bass Coast project last year, was also heartened by Dr Hawke's calls.