Greenwich is an openly gay male MP in the NSW Legislative Assembly. Before entering politics, Greenwich was a prominent
LGBT rights activist and led
Australian Marriage Equality (AME). Prior to running for office, Greenwich was the national convener of AME from 2009, and in 2010 was named as one of Samesame.com.au's 25 most influential gay and lesbian Australians. As national convener, Greenwich organised over 44,000 submissions to be made to the 2011
Australian Senate inquiry into same-sex marriage, and continues to be a prominent activist for achieving
same-sex marriage reform in Australia. As of 2017 Greenwich has triple Australian, New Zealand and United States citizenship. Shortly before this was publicised, Greenwich had renounced his New Zealand citizenship. For WorldPride, Greenwich swapped his signature casual suit and shirt for a tuxedo with green tulle in a display that was hosted in the QVB.
Lawsuit against Mark Latham In May 2023, Greenwich announced he would be launching defamation action against the then-leader of One Nation NSW,
Mark Latham, for a graphic and homophobic tweet about Greenwich. Latham's tweet was widely criticised, with Prime Minister
Anthony Albanese saying that "hateful speech" was never warranted, and One Nation founder and leader
Pauline Hanson describing the tweet as "disgusting". Latham's tweet was a response to Greenwich, who criticised Latham over an event he was speaking at where pro-LGBT protesters demonstrating against his appearance were rushed by hundreds of men. On 11 September 2024, the
Federal Court ruled that the tweet was defamatory. Judge David O'Callaghan found that the tweet was defamatory because it made Greenwich out to be a person that "engages in disgusting sexual activities". He rejected Latham's
defences, a statutory defence of honest opinion and a common law defence of qualified privilege, right of reply to attack. Greenwich also claimed that the tweet conveyed that Greenwich was not a fit and proper person to be a member of the
New South Wales Parliament, however the judge found that allegation not proven. The court awarded Greenwich $140,000 in damages. Greenwich praised the judgement, saying "It gives me confidence that we've established some case law here that can protect other LGBTQ people", and that "The strength of this judgment is that... it is made clear that this
Trump-style political attack on your opponents based on their sexuality, based on whatever you want to attack them for, has no place in the Australian public political discourse". In an interview with
DNA magazine published in their November 2025 issue, Greenwich stated that he had been diagnosed with
post-traumatic stress disorder (PTSD), in the aftermath of Latham's comments and subsequent death threats directed towards him. Greenwich also said that he had been prescribed
medical cannabis to deal with symptoms of PTSD, such as anxiety and insomnia. In April 2026, Latham was found to have defamed Greenwich by the
NSW Civil and Administrative Tribunal (NCAT) for an offensive
tweet made in 2023. NCAT required Latham to pay Greenwich $100,000, to delete any offensive social media posts and to refrain from harassing Greenwich further. ==Political career==