Chief Justice Margaret Marshall of the Massachusetts Supreme Judicial Court, now retired, was responsible for a landmark 2003 ruling that denying same sex couples the right to marry was a violation of their constitutional rights.
"I wouldn't judge another nation," she said of Australia's upcoming postal survey on same-sex marriage, "but I am surprised that people anywhere in the world don't understand yet what it means for people to love one another.
"It doesn't matter what their gender, what their origins, where they come from," she added
"I just hope that we won't have to wait for too much longer before everyone in the world can be in love with and marry who they choose to."
She was speaking to SBS World News at the London revival of a Pulitzer-prize winning play, 'Angels in America', which tackles fear and prejudice at the height of the 1980s AIDS crisis.
At the premiere performance on August 16, the cast of the self-described "gay fantasia" gave Chief Justice Marshall a standing ovation.
She was immediately mobbed by tearful members of the audience.
"Thank you," were the only words most could muster.
Backstage, actor James McArdle, who portrays the character Louis Ironson in the play, recited the most famous passage of her 50-page judgement.
"Civil marriage is an esteemed institution and the decision whether and whom to marry is among life's momentous acts of self-definition."
Mr McArdle was less diplomatic about the tone of Australia's same sex marriage debate.
"The fact that this has been given to the public as 'an opinion' I think is an insult. I really think it's insulting. The fact we're even having this discussion I think will be an embarrassment in years to come."
Same sex marriage has been legal in England, Wales and Scotland since 2013.
A decade before her landmark ruling, Margaret Marshall sat in the very same theatre for the premiere of 'Angels in America' - a form of artistic activism, transporting audiences to 1980s America and the height of the AIDS crisis.
It had a profound, personal impact, so she returned 25 years later, to witness its 21st Century revival.
The former Chief Justice told SBS that many of its themes - sexuality, race, gender, inequality, nationalism, fear and prejudice - remain just as fraught today.
"I think there is a hint of sadness that everything still feels as if we have so far to go," she said.
Australians will have the chance to watch the UK revival of 'Angels in America' when the two-part, eight-hour performance is beamed live from the National Theatre to cinemas across the country throughout September.
