The federal government has lodged a writ in the High Court challenging the ACT's new gay marriage legislation.
No hearing date has yet been set, but a High Court spokesman said there could be a directions hearing next week, with the possibility of the case being heard before the end of the year.
The case is a constitutional matter within the High Court's original jurisdiction, so the commonwealth won't have to apply to the court for special leave for its case to be heard.
The federal government says it has asked for an expedited hearing to avoid any distressing people who may marry under the laws, only to find their marriage is not legal.
"If as I think the ACT legislation turns out to be invalid under the Constitution, well then those marriages wouldn't be valid," Mr Abbott told 3AW.
"So I'd suggest to people who would like to be married under the ACT legislation - hold on 'til its validity is tested."
The writ documents say the ACT Marriage Equality (Same-Sex) Act 2013, which passed the ACT legislative assembly on Tuesday, is inconsistent with the Commonwealth Marriage Act 1961.
The Marriage Act 1961, it says, establishes the sole and exclusive means under Australian law by which the status of marriage may be attained.
In the writ, the commonwealth said this case should be heard as soon as possible to reduce or avoid uncertainty over the ACT legislation,
"The uncertainty is exacerbated to the extent that persons may wish to enter into marriage under the ACT Marriage Act before its validity has been determined," it said.
The commonwealth is proposing the case be ready to proceed by late November.
That's on the basis that the earliest any marriage could be performed under the ACT law would be in December.
