Prime Minister Scott Morrison has rightly savaged a “ridiculous” move in Tasmania to make inclusion of a baby’s gender on a birth certificate an “opt-in” decision for parents.

The changes passed Tasmania’s lower house on 20 November, after rogue Liberal Speaker Sue Hickey voted with Labor and the Greens in favour of the radical changes.

The bill also allows people 16 or older to change the gender on their birth certificate simply by filling out a statutory declaration – and an amendment to Tasmania’s anti-discrimination laws, designed to ensure the "correct" use of transgender people’s names and honorifics, was also passed.

The Prime Minister, along with most of his Tasmanian Liberal colleagues, opposed the move.

“Labor’s plan to remove gender from birth certificates in Tasmania is ridiculous,” Mr Morrison tweeted.

“Bill Shorten should step up and commit to put motion to ALP Federal Conference to outlaw it.”

How did this happen?

It’s worth taking a step back to examine how an Australian state has come to vote on legislation that essentially denies the reality of gender.

Most readers would be completely unsurprised to know that the move came about as a direct result of last year’s redefinition of marriage.

Because of changes to the Marriage Act, if transgender people who had already married wanted their birth certificates changed in Tasmania, they were required to firstly divorce their partners and then re-marry after the gender change.

In mid-October, Tasmania’s Liberal Government proposed changes to legislation to remove this requirement.

The Greens then hijacked the bill, proposing radical amendments that included removal a child's gender from all future Tasmanian birth certificates.

According to the Greens proposal, gender should not be included on Tasmanian birth certificates. However, a child over 16 could have it added by making a statutory declaration. For children under 16, a statutory declaration would be required from one of the child's parents or legal guardians and the order must “express the views of the child” (whatever that means).

This seemed like total nonsense, of course – but their proposal was initially supported by the Tasmanian Labor Party.

Despite not having the support of the Tasmanian Government, the Greens amendment looked likely to pass. This is because the Government relies on the casting vote of Speaker Sue Hickey, who although Liberal, was elected to the position with Greens and Labor support and votes as an independent.

In early November, after Prime Minister Scott Morrison attacked Opposition Leader Bill Shorted over the radical nature of the federal Labor Party’s 2018 draft policy document, the Tasmanian Labor Party backed away from supporting the Greens amendment.

While this effectively killed the Greens amendment, Labor then proposed its own amendment – one that argued instead that parents should be able to decide what is written on their child’s birth certificate.

“It’s about giving parents a choice about what they see as relevant on their child’s identity document,” said Labor justice spokeswoman Ella Haddad.

In other words, Labor considers the “choice” of parents to be more important than biological reality.

The state Liberal Government continues to oppose the legislation. Attorney-General Elise Archer said the amendments are deeply flawed.

“This amended bill contains legally untested, unconsulted and highly problematic changes that we could not support,” she said in a statement.

“No other state or territory in Australia has taken the step proposed of removing gender from birth certificates,” said Attorney-General Elise Archer.

“For Tasmania to do so, in the absence of any proper consideration of the reform, exposes the state to a range of potentially serious unintended consequences.”

Feminist group Women Speak Tasmania has also raised serious concerns that men would pretend to be women to access certain spaces, such as women’s refuges.

“We are concerned the rights of women and girls to safe female-only spaces will be collateral damage in the rush to allow male transgender persons to become legally female simply by signing a declaration that they identify as female,” the group said.

Meanwhile, transgender rights groups, along with the Greens and Labor, appear to be completely ignorant of both biological reality and women’s rights.

The Tasmanian Labor Party’s justice spokeswoman, Ella Haddad, said it was a great outcome on the back of the “marriage equality” vote that wouldn’t diminish the rights of others.

And Greens leader Cassy O’Connor told parliament the changes “will make people, who we should all care about, feel happier, safer and more included”.

This legislation will now move to Tasmania’s upper house for debate and vote.