Simon Corbell.

ACT Attorney-General Simon Corbell. Photo: Rohan Thomson

Transgender people in Canberra are set for a landmark win this week when the ACT government passes laws allowing them to change the sex on their birth certificate.

To date, a birth certificate can only be changed where someone has had sexual reassignment surgery.

But the new laws will allow someone to identify as male, female or ''X'', without surgery.

All they need is for a doctor or psychologist to certify they have received ''appropriate clinical treatment'' - which is deliberately not defined, leaving it to the doctor or psychologist.

The legislation is set to be debated and passed on Thursday.

The Liberals have yet to decide how they will vote, their leader Jeremy Hanson saying a decision will be up to the party room on Monday.

He had met the lobby group A Gender Agenda and said his eyes had been opened to the complexity and sensitivities of the issue.

Attorney-General Simon Corbell said people who had changed their sex faced embarrassment and an invasion of privacy in day-to-day situations when their birth certificate recorded a different sex.

''Transactions that most of us take for granted every day can become humiliating, embarrassing or simply impossible because of the conflict that currently exists between a person's outwards gender identification and how that is legally recorded on their birth certificate,'' he said.

The legislation will also extend the time limit for births to be registered from 60 days to six months.

This gives parents time to decide how to register the sex of their child in cases when the baby is not clearly male or female.

The new law will allow parents to have their child's birth certificate changed if they believe it in the best interests of the child and when the child has received ''appropriate clinical treatment'' - again, without the need for sexual reassignment surgery.

A new category on birth certificates brings ACT birth certificates into line with Australian passports, allowing people to opt for ''X'', instead of either male or female on their birth certificate - a category for people with indeterminate, intersex or unspecified sex.

''Instead of requiring black and white distinctions that categorise rather than empathise, that allow for easy administration but not true inclusion, the ACT recognises sexual diversity,'' Mr Corbell said.

And it changes the rules about when an original birth certificate - before the change of sex - can be issued.

A parent (or person with parental responsibility) for the person, an executor of someone's estate, or a child of the person will be able to request an original birth certificate.

But spouses or former spouses (and partners) will no longer be able to make the request.

After the legislation was introduced last year the Assembly's standing committee on justice and community safety questioned whether any form of clinical evidence should be necessary, suggesting that self-identification alone could be sufficient.

It questioned whether there was sufficient protection for children whose parents changed their birth certificate, and it asked the government to consider the case of children who want to change their birth certificates without the support of their parents.

None of those issues, though, have been incorporated in the legislation.