The Australian Psychological Society (APS) decided to officially support it.
This decision is based on the fact that to pass gay marriage has positive effects on mental health.
"Decades of psychological research provides the evidence linking marriage to mental health benefits, and highlighting the harm to individuals’ mental health of social exclusion. The APS supports the full recognition of same-sex relationships, on the basis of this evidence," Professor Simon Crowe, president of APS, explained.
Dr. Damien Riggs, convenor of the APS Gay and Lesbian Issues in Psychology Interest Group, added: "Marriage discrimination has a flow-on effect on same-sex attracted Australians, their loved ones, and the wider community. Psychologists must work to ensure that all Australians are supported to achieve positive mental health and full social inclusion."