ACT Liberal Senator Gary Humphries says it is only fair that the Federal Government step in and override the territory's civil unions bill.
When passed, the legislation will give same sex couples in Canberra legal rights under territory law.
Senator Humphries has rejected a call by the ACT's Labor senator and Labor MPs to support the plan.
He says there does not appear to be any difference between marriage and what the ACT Government is proposing as a civil union.
"To that extent I think it is going beyond its power as a territory, it's going beyond the power that any state would have to legislate in that way and if that's the case the Commonwealth is quite within its rights to say, 'you're not entitled to do this, you won't be allowed to do it'," he said.
Meanwhile, the peak body representing Australia's civil celebrants fears the range of services offered by their members may be eroded if the Federal Government overrides the ACT plan for civil unions.
http://www.abc.net.au/news/newsitems/200603/s1605195.htm