Tasmania is making gender optional on birth certificates.

The state’s Lower House has passed the Marriage Amendments Bill after Liberal speaker Sue Hickey voted with opposition parties to bring forth debate.

The Liberal Government opposes the amendments and says the Bill was hijacked by Labor and the Greens, was sloppily drafted, and could have unpredictable (and undefined) consequences.

The legislation makes specifying a gender on birth certificates optional, and removes a requirement for transgender people to have surgery in order to have their gender recognised.

People aged 16 years or older will be able to apply to change their registered gender without parental approval, and laws have been expanded to allow individuals to freely express their gender without discrimination.

The legislation passed to decidedly low-key celebrations.

Martine Delaney from Transforming Tasmania said it was almost anti-climactic.

“All this will do is make a positive difference to the lives of young trans and gender-diverse people,” she said.

“It's been something that's taken so long and it's been such a struggle over the past 12 months, with the Government not at all supporting us, but we've got there.”

Ms Hickey expressed her support for the amended legislation.

“This is indeed an historic occasion,” Ms Hickey said.

“I believe wholeheartedly that this Bill removes the discrimination of the transgender community and the only unintended consequence would be that a failure to pass this legislation would result in more psychological damage to the transgender community and their families.

“This is not a win for any particular political party, rather it grants dignity to the transgender community.”

The Catholic Church-backed Tasmanian Coalition for Kids, and the Australian Christian Lobby (ACL) want the legislation repealed.

ACL spokesperson Ben Smith said many Tasmanians would oppose the changes, if they knew about them.

“We have no doubt that when the broader community becomes aware of the negative impact of these changes, that the case for repealing these changes will become overwhelming,” Mr Smith said.

Premier Will Hodgman appeared to back that view.

“Because of the refusal by Labor and the Greens to consider the legal consequences of their amendments, it is highly likely the Parliament will need to fix up problems with the legislation, and [it might mean] repeal of the Labor-Green amendments at a later date,” he said.

None of the opponents have given a clear argument on what these ‘negative impacts’ or ‘consequences’ might be.