Legal challenge looms for NSW protest laws

AAP

The NSW union movement is considering launching a High Court challenge to the state government's controversial new anti-protest laws.

With support of the Shooters, Fishers and Farmers Party and Christian Democrat Fred Nile, the laws passed the upper house with minor amendments on Wednesday.

The bill gives police greater powers to search without a warrant, seize items or move on protesters while fines for illegal entry to mining and CSG sites have increased tenfold from $550 to $5500.

Anti-CSG protesters who interfere with gas sites - including those who chain themselves to machinery - will also now be exposed to a maximum jail sentence of seven years.

Greens MP Jeremy Buckingham, who along with Labor voted against the legislation, condemned the changes as a "jack-boot police crackdown on democratic rights".

But Premier Mike Baird defended the legislation on Wednesday, saying he didn't believe they were too harsh.

About 500 protesters shut down a part of Sydney's CBD to rally against the proposed changes on Tuesday.

The NSW Law Society said lawyers were concerned the legislation could seriously interfere with people's human rights liberties.

Unions NSW says it's considering launching a constitutional challenge against the laws.

"We will happily march back to the streets and the High Court to defend the entitlements of any protester to exercise their democratic right to freedom of political communication," Unions NSW secretary Mark Morey said.