Hundreds of people who rallied in Tasmania today against proposed anti-protest laws have been warned the State Government intends to misuse the prison system.

More than 500 people packed into Hobart's City Hall to protest against laws that would see on-the-spot fines and jail sentences for people who disrupt workplaces.

Former Greens leader Bob Brown labelled the laws discriminatory and out-of-balance, telling the crowd that: "These laws would have jailed Gandhi and Jesus Christ himself."

Many see the laws as aimed at anti-forestry protesters, who have disrupted logging in state forests by protest actions.

Richard Griggs from Civil Liberties Australia told the rally the proposed laws would create mandatory prison sentences for people who on two occasions gathered on public land to protest, if they slowed or hindered a vehicle registered to a business.

"This is a misuse of the prison system by our Government. Prisons should be used by government to make the community safer, not as a way to frighten the community into silence," he said.

He said competing rights of workers to enter their workplaces, and those of people have a right to protest, were currently managed by the laws of trespass and public nuisance.

Mr Griggs said people were at the rally to stand up for the right to peaceful protests, which was a fundamental democratic freedom.

Greg Barns from Australian Lawyers Alliance agreed, saying: "You can be 18, 19 years of age, you're fired up at a protest, and you decide to run into some business premises, you end up getting a mandatory conviction. I will not be bullied or cowered by their brutal strategy."

Previously, the Greens have compared the laws to those of Nazi Germany, while Labor's Lara Giddings has described the legislation as draconian.

The State Government rejects the criticisms.

Resources Minister Paul Harriss said the protest showed there was no issue with peaceful demonstrations.

"The legislation currently before the Parliament does in no way diminish or take away from the opportunity for anyone to peacefully and legally protest." he said.

The bill has passed the Lower House and will now be considered by the independent-dominated Upper House.