Former Greens leader Bob Brown is warning Tasmanians to expect "bad karma" over the likely passage through the state parliament of new anti-protest laws.

The Government's plans to crack down on protesters who trespass on workplaces were heavily amended in the Legislative Council.

Mr Brown, who took part in the country's key environmental battles, warned the tougher laws would not stop protesters.

The long-term environmental campaigner is also worried the maximum four-year jail sentence for trespass is too harsh.

"The four-year jail sentence for nature lovers, people who defend Tasmania's forests peaceably, are totally out of kilter," he said.

"That's a worse penalty for nature lovers than people who fail to go to the defence of a distressed child, than people who negligently drive leading to the deaths of other citizens," he said.

"It's legislation that you'd think would be more at home in Putin's Russia than in (Will) Hodgman's Tasmania. They're simply a recipe for bringing bad karma and a bad look for Tasmania."

Amended protest laws: What's in: Maximum four-year jail term for workplace trespass

Maximum four-year jail term for workplace trespass Applies to any workplace in Tasmania

Applies to any workplace in Tasmania On-the-spot fines for workplace trespass

On-the-spot fines for workplace trespass All sentences at court's discretion What's out: Mandatory minimum fines for trespass

Mandatory minimum fines for trespass Mandatory jail terms for repeat offenders

Mandatory jail terms for repeat offenders Maximum two-year jail term for workplace trespass

Maximum two-year jail term for workplace trespass Application limited to forestry, mining, construction, agriculture and manufacturing sectors

Under the changes, mandatory fines and minimum jail terms have gone.

In their place, the laws were broadened to cover all workplaces and the maximum prison term has been doubled from two years to four.

The Government spent months talking up proposed tough minimum sentences including on-the-spot fines of up to $10,000.

On Thursday night, the Government agreed to a raft of amendments in the face of Upper House resistance.

The Government was disappointed the Upper House did not respect its mandate to bring in minimum sentences for illegal protesters.

But MLCs took a dim view of parts of the plan and the Government was forced to cede ground.

The Government insisted the amended laws would still be the strongest in Australia.

Amended bill 'a dog's breakfast'

The laws are aimed a protesters who disrupt workplaces like forestry coupes. ( Zoe Polacik: ABC News )

Labor's leader in the Upper House, Craig Farrell, labelled the bill a "dog's breakfast".

"I've been reading through my patched up copy - had to have a bit of a break from it because it's all over the place," he said.

Resources Minister Paul Harriss denied the amendments had embarrassed him but said he was disappointed.

"It wasn't a backdown," he said.

"[I'm] disappointed that the Legislative Council didn't see fit to uphold what we would clearly say is a mandate. We took this to the election, there was no ambiguity about this whatsoever."

"The core principles here are to protect workplaces and the workers who work in them getting about their opportunity to do what they legally ought be able to do.

"Now that is the core principle which the bill set about achieving and that's been achieved.

"If people don't break the law, and if they go about legally and peacefully protesting as they have been able to up to now, and as they will be able to in the future, then there's no risk of them being prosecuted.

"The law doesn't apply unless they choose to be illegal."

The bill still needs to be put to a vote in the Upper House before a final sign-off from Parliament's House of Assembly.