The Australian Capital Territory (ACT) will be forced to defend its newly implemented equal marriage law starting Tuesday as the country’s High Court will hear a legal challenge to it.

The highest legal jurisdiction in Australia, a full bench of the court, will hear a challenge from the Commonwealth which seeks to have the same-sex marriage bill, which was approved in the ACT in October, struck down.

The Commonwealth is to ask the court to consider eight questions in arguing that the new law violates the federal Marriage Act, which it sees as a sole code to obide by.

The ACT, however, will defend the legislation, arguing that individual states and territories may legalise equal marriage.

Same-sex marriage advocates are expected to attend the Canberra court on Tuesday.

Despite having a gay siblingAustralia’s Prime Minister Tony Abbott continues to oppose equal marriage and has supported efforts to halt the ACT’s equal marriage bill in the courts.

In October,, Mr Abbott said that the ACT court challenge was about upholding the Australian constitution and about preserving a “uniform approach throughout the commonwealth” to marriage laws.

Earlier, several amendments were made to the ACT’s bill in order to safeguard its legal passage. 

Same-sex couples living in the ACT have been allowed to register their partnerships since 2008 and hold civil partnership ceremonies since 2009, when the ACT became the first territory in Australia to introduce such legislation.

Equal marriage remains banned at a federal level in Australia and efforts to legalise the measure failed in the Australian Parliament in September 2012.

Christine Forster, the sister of Mr Abbott, has revealed that she has proposed to her partner Virginia Edwards.