A High Court challenge against Tasmania's anti-workplace protest laws looks set to be heard later this year, after a second plaintiff joined the case.

Former Australian Greens leader Bob Brown launched a challenge to the legislation after he was among the first five people charged during a protest against logging at Lapoinya in the state's north-west.

When police dropped his charge due to a technicality, Forestry Minister Peter Gutwein said the Government would push to have the case thrown out.

But in a hearing today, fellow Lapoinya protester Jessica Hoyt became a co-plaintiff in the case.

Mr Brown suggested the Government had had a rethink because it would have lost an attempt to block her application to join the case.

"Their legal advice was they would not be able to maintain that objection," he said.

"They were challenging our standing, both the standing of myself and the standing of Jessica Hoyt. That objection is now in abeyance."

Mr Brown said Ms Hoyt's participation broadened the case against the legislation.

"She was arrested before I was and she was arrested because she went back to the site, rather than refusing to leave the area and these are different components of this legislation," he said.

Tasmania Police dropped charges against the five Lapoinya protesters due to technicalities, such as errors over the location of the protesters at the time of their arrest.

The next hearing has been set for September 6.

The State Government have been contacted for comment.

Mr Gutwein has previously said he was confident the laws would stand up to challenge and future charges laid under the legislation would stick.