In all the ways that matter to him Paige Phoenix is a man. The only gender confusion he wrestles with is that inflicted upon him by the agencies that govern his life.

Born female, he has lived as a man for seven years, having a double mastectomy and taking testosterone to help him express outwardly what he feels on the inside. It allowed him to change his passport to male. But Victorian gender laws are more prescriptive. To change his birth certificate he was told he would require sex reassignment surgery.

The 38-year-old, who has a serious medical condition that makes reproductive surgery risky, ruled it out. His choice did not diminish his sense of masculinity. But when he wanted to marry his long-term girlfriend, the decision came back to haunt him.

Legitimately using his passport as an identity document to satisfy the celebrant’s requirements, he embarked on ''the happiest day of my life''. Three weeks after the wedding in 2012 he received a letter from Births Deaths Marriages Victoria informing him that a cross-check with his birth certificate had revealed he was female. Under the act, marriage was between a man and woman. Their union was invalid. He was asked to return the marriage certificate for ''destruction''.

''Culturally, we have such an emphasis on defining gender by genitals but if you walked past me on the street you wouldn’t know that I hadn’t been born male. I’m not female and I should have the right to have my documents reflect that,'' he says.

Paige’s experience is only the edge of a legal and bureaucratic minefield that civil rights activists are calling the next frontier in the fight for equality. As more transgender people take steps to live openly as their authentic selves, they are increasingly clashing with laws that fail to support them.

At federal level, Australian legislation is heralded as among the most progressive in the world but state and territory laws lag, leaving many battling a system that is at best inconsistent and outdated, and at worst punitive.

''Those sorts of inconsistencies are not just theoretical paperwork inconveniences - they ground themselves in very real impacts for people like me. When we’re forced to do things like go under the knife and have life-threatening surgery in order to have our sex recognised, it’s ridiculous,'' Paige says.

While the couple have since separated, partly due to the stress the marriage annulment put on their relationship, Paige is taking his case to the United Nations Human Rights Committee, arguing that requiring a person to have irreversible, invasive surgery to change their gender on a government form is a fundamental violation of human rights.

It is among a number of challenges to state birth, death and marriage laws that aim to end discrimination and question the very concept of what it means to be male or female or neither, and whether, in a diverse modern world, gender is even relevant.

''You don’t buy an airline ticket and fill out whether you’re of south-east Asian descent or Anglo-Saxon, so why does an airline or a bank need to know whether you’re male or female?'' says Anna Brown, director of advocacy and strategic litigation at the Human Rights Law Centre, who is leading the legal push.

''For a transgender person, even filling out the most basic form can be difficult and distressing, so reform to identity documents would make a huge practical difference to their day-to-day lives and it would also pave the way to reducing discrimination, stigma and social exclusion.''

Last year, gender identity was thrust into the spotlight when ''Norrie'' became the first person in NSW to be neither man nor woman in the eyes of the state government.

The 50-year-old Sydneysider who was born male and goes only by first name, won a NSW Court of Appeal case to have the designation ''sex not specified'', overturning a ruling that everyone must be listed as a man or a woman with the Registry of Births Deaths and Marriages.

Norrie’s three-year battle ended with a three-judge appeal panel unanimously declaring that ''as a matter of construction ... the word sex does not bear a binary meaning of 'male' or 'female'.''

The legal precedent has emboldened campaigners who say that rigid definitions of gender are archaic and that a person’s sex should not be determined solely by their reproductive organs.

They want changes to laws that require reassignment surgery – in every jurisdiction except the ACT, which amended legislation this year – before a person’s sex can be changed on their birth certificate. It means people who identify as the opposite gender to that of their birth, must undergo ''sex affirmation'' surgery, in order to be recognised as their true selves in the eyes of the law.

In Victoria, while some doctors will sign off on a female-to-male sex change based on chest surgery alone, according to the Birth, Deaths and Marriages Act sex affirmation surgery is defined as ''alteration of a person’s reproductive organs carried out for the purpose of assisting the person to be considered a member of the opposite sex''.

While a legal challenge to similar Western Australian laws enabled transgender men who had top-only surgery and hormone treatment to be recognised as men, there is confusion around what exactly constitutes a ''reproductive organ'' under Victorian law, and it has not yet been tested in court. After having chest surgery, Paige was told by Births Deaths Marriages Victoria he still did not meet the requirements for change of gender.

A spokeswoman for the registry said that applicants must provide two statutory declarations from surgeons to confirm sex affirmation surgery had been performed but it was up to individual doctors to determine what that constituted.

Anna Brown maintains that clarification of the act's wording is needed to ensure transgender people do not have to suffer through the uncertainty and expense of litigation simply to be recognised as themselves.

The restrictive rules are in direct conflict with federal policy, which former prime minister Kevin Rudd relaxed in 2011 to reduce discrimination. Not only did it give passport holders a third gender option of X (unspecified), it allowed passports to be issued in a new gender without the requirement for any surgery.

Applicants must provide only a letter from a medical practitioner to certify that they are being treated for transition to a new gender.

They can also state they are, as Norrie wishes to, ''unspecified, indeterminate or intersex'' – meaning they were born with a combination of male and female sex characteristics and wish to identify as neither or both, or were born as a biological male or female but have grown up to identify as neither exclusively.

The push reflects a growing shift towards the rejection of traditional binary male/female roles. As with many social change movements, young people are at the forefront.

The ''Gender Is Not Uniform'' campaign led by Minus 18 – a Melbourne youth-run organisation for gay, lesbian and trans young people – encourages schools to make uniform policies more flexible to support students exploring their gender identity.

Similarly, the Safe Schools Coalition – a national program to protect gay, lesbian and trans children from bullying and discrimination – last month launched a campaign encouraging schools to allow students to wear any uniform garment regardless of gender. It provided advice to Carrum Downs Secondary College in Melbourne when their 17-year-old student, Mia, who recently told her story in The Saturday Age, transitioned from male to female with the school’s support.She said not being allowed to wear a school dress would be distressing.

In Canada, attitudes towards gender non-conformity are even more progressive, with a school board in Vancouver last month introducing a policy allowing pupils to be referred to as ''xe'' (pronounced zee), ''xem'' and ''xyr'' instead of he or she or him and her, and letting students choose which toilets they use including a mandatory unisex option.

While to some, it might seem a peculiar concept, Lisa Sinclair from Gender Queer Australia says that as society becomes more open-minded, gender pronouns will eventually be rendered meaningless. ''People should just be able to identify as a human being and be done with it. It’s just an arbitrary label based on the absence or presence of genitalia. It’s used to pigeonhole people into one set of jobs or one set of abilities for no good reason.''

Likewise, Sally Goldner from Transgender Victoria – who was born male but identifies as female and takes hormones but feels no need for surgery because “I don’t need it to be who I am” – says deep-rooted assumptions that male and female are the only two points of gender expression are outdated. “The reality is gender identity is a kaleidoscope, it’s an infinite number of dot points and everyone’s is unique.''

Yet, while gender may be a fluid concept, the bureaucratic machine is less malleable. Inconsistencies with identity documents lead to problems for many transgender people when dealing with agencies that use birth certificates as a form of ID, such as Medicare, Centrelink, or even when trying to change a name on a bank account.

For 29-year-old transgender man Canon O’Saurus, it has been an emotional fight to be recognised as his true self. ''Think of the most personal thing there is about you, and imagine going and telling every stranger you met that personal thing and anticipating their response. I can leave places and just be distressed for days after some of those experiences,'' he said.

As a student at Monash University he used a doctor’s certificate to be acknowledged as a male student. But changing his gender at Centrelink, where he was receiving a student payment, proved more difficult. Staff told him he would need to change his birth certificate, which would require surgery he could not afford.

When his details at university and the welfare agency did not match, payments were cut off, forcing him to attend a Centrelink office to consolidate the two. After making an official complaint, he learnt that transgender people needed a doctor’s certificate, not surgery, to change their gender with Centrelink. Now he is pursuing a legal case, contending that clients should not need to identify any gender to receive benefits.

These situations should be minimised under new Australian government sex and gender recognition guidelines, released last year for all federal departments and agencies. The aim is to develop a consistent sex and gender classification system for all government records in a bid to reduce discrimination and distress. Agencies have until July 2016 to comply with the new rules.

But it will not resolve state-based birth certificate rules that tie gender change to surgery. It is a fixation that Fintan Harte, director of the Monash Gender Dysphoria Clinic – Australia’s only adult sex reassignment service – says is at odds with reality, as only a third of transgender people feel compelled to go under the knife.

''There’s a variety of ways of exploring gender expression without resorting to physical treatments,'' Dr Harte says. ''The World Professional Association for Transgender Health has a position statement that no patient should be required to have invasive major surgery just to change a form, and that’s what we should be following.''

But for those who want full gender reassignment surgery legal hurdles remain. Campaigners are increasingly concerned about the growing phenomenon of ''forced trans divorce'', in which married couples are forced to legally separate if one partner changes sex.

Greens MPs in NSW and South Australia are challenging ''cruel and dehumanising'' laws that mean happy couples must choose between ending their marriages to have the transitioning partner recognised as their affirmed gender on their birth certificate, or live with identity documents that do not match their true sex.

As a growing population of transgender young people fights for their rights, these emerging issues cannot be ignored by governments and legal systems.

Figures obtained exclusively by The Sunday Age show that the number of children accessing medical treatment to help them change sex at Australia’s only clinic for transgender young people has increased 60-fold in a decade.

The Royal Children’s Hospital gender dysphoria service is buckling under demand and many of those seeking help are facing similar legal red tape to older generations.

While the hospital can provide puberty-suppressing drugs without a court order - usually from the age of 11 onwards providing there is parental consent - Victoria is one of the few jurisdictions in the world that requires court approval for stage two hormone treatment to help patients develop characteristics of their affirmed gender.

Long-term use of puberty blockers can cause osteoporosis, meaning patients usually stop taking them at 16. But without access to hormone therapy they will revert back to their birth gender, causing significant distress.

The court costs are often upwards of $20,000. Melbourne mother-of-three Therese spent her life savings seeking Family Court approval for 17-year-old son *Sam, who was born female, to receive testosterone. Had they lived in NSW no court order would have been required because the age of consent for medical treatment there is 16.

''It’s one country. It’s just so unfair that the rules are different for medical treatment. It doesn’t matter to me whether he’s a girl or a boy as long as he’s healthy. All that counts is he’s still here, he’s alive, and he’s happy in his skin.''

For Sam, who began hormone injections a month ago, the politically charged nature of transgender issues is frustrating. ''How are you going to explain to a four-year-old that what you’re feeling is all politics? I just want a normal life where I can finish school, go to uni, get a job, get a house maybe have a dog. I want to feel right in myself and live my life like everyone else can.''

* Name has been changed.