Sarah-Jayne is a Major in the Australian Army and has served with distinction since 2000.

She works in the health area and has had active deployments in Bougainville and East Timor.

She was sent to Aceh to provide medical aid after the 2004 Boxing Day Tsunami.

She has facilitated training courses and run health clinics at Army bases.

But in the United States military, Sarah-Jayne would not be allowed to serve. She is transgender, having transitioned in 2012.

Trans people excluded from ADF until recently

The Australian Defence Force (ADF) also used to discharge any member who intended to transition.

In 2010, Army Captain Bridget Clinch challenged her discharge with the Australian Human Rights Commission. The ADF reversed her discharge and repealed its transgender ban.

Since then, trans and gender diverse personnel have slowly come out across the Navy, Army and Air Force.

Australia is now in the company of at least 18 nations that permit open transgender service, including close allies New Zealand, the United Kingdom and Canada.

In 2016, President Obama began the process of lifting America's transgender military ban. But in mid-2017, President Trump announced that the ban would continue. Activists immediately challenged this in the US courts.

This week's 5-4 Supreme Court ruling said the ban will remain in place while the cases work their way through the courts.

Civil liberties and rights groups are challenging Donald Trump's ban on transgender people serving in the military. ( Reuters: Jonathan Ernst )

Australia leading the way

If America looked to Australia's recent history, it would see the many contributions that transgender service members bring to the nation's defence.

Those whom I've interviewed for a project on the LGBTI history of the ADF have served as infantry officers, ground defence officers, photographers, band members, in logistics, in personnel and maintaining aircraft weapons systems. They have served in East Timor, Iraq, Afghanistan and across Australia.

Since lifting the ban, the ADF has gradually adopted policies to support transgender members. A series of handbooks designed with transgender members provide guidance to commanding officers and to transgender personnel themselves. They address topics such as uniforms, toilet access, pronoun usage and strategies for how to come out.

Like in the United States, social conservatives in Australia have been vocal in their opposition to transgender service. They draw on similar arguments as Trump, but evidence debunks their claims.

A rainbow wreath used to commemorate LGBTI military service. ( Supplied: Daniel Spellman/Defence Gay and Lesbian Information Service )

Myth 1: Transgender surgeries and medical needs are too expensive

Between November 2012 and July 2017, the ADF funded gender dysphoria treatment for 32 ADF members, including surgery for 17 of them.

The $1.16 million bill is miniscule — 0.006 per cent of Defence health expenditure.

The money spent on training and the work that each ADF member performs far outweigh these costs.

Myth 2: Transgender troops may hurt morale or unit cohesion

This is the same argument used to oppose lesbian, gay and bisexual service before November 1992.

Transgender personnel have reported varying levels of peer support, with officers and trans men tending to have better experiences than trans women and other ranks.

One theme that permeates interviews with transgender personnel is that strong leadership can support all members of a unit.

Australia is now in the company of at least 18 nations that permit open transgender service. ( ABC Radio Sydney: Luke Wong )

Myth 3: Transgender people have a mental illness

In June 2018, the World Health Organisation removed being transgender from its list of mental illnesses.

Gender dysphoria is one of many health conditions that serving ADF members may have.

The ADF provides health care to all its members, and since April 2015 a specific policy has outlined treatment processes for members with gender dysphoria and those undergoing transition.

Myth 4: A social engineering experiment with special privileges

The inclusion agenda is not social engineering. Welcoming transgender members and ensuring that they are treated with dignity and respect does not take away from the respect afforded to other members.

Perhaps the biggest lesson to take from the ADF's shift towards transgender inclusion is that transgender members are not problems or burdens.

As all five Defence chiefs wrote in a 2016 letter to The Australian:

"Diversity is not about identity politics, it is about improving the quality of the workplace. It's the antidote to group think — gaining a wider range of perspectives to make better decisions and, in the military context, enhancing our capability, that often intangible concept that is manifest in the conduct of military operations."

Noah Riseman is a historian at ACU and co-author of Serving in Silence? Australian LGBT Servicemen and Women. He is currently conducting a project researching the history of transgender people in Australia.