Australia's chief medical officer does not support the legislation of cannabis in the ACT, saying more evidence is required about its impact on health.
The territory became the first Australian jurisdiction on Friday to legalise the drug in small amounts for personal use. Canberrans will also be able to cultivate up to two plants.
The law is not supported by the federal government, although it is not seeking to overturn the legislation.
Health Minister Greg Hunt said, "We don't support it, but it's a matter for the ACT."
Chief Medical Officer Brendan Murphy said he supported the federal government's position on the drug.
"I think cannabis has a medicinal role and the evidence suggests we need much more data," Professor Murphy said.
"It needs a lot of evidence about its role in health, and that's being done under a proper medicinal access."
Technically, cannabis is still considered a controlled substance in the federal criminal code, which comes with far steeper penalties than those previously in force in the ACT.
The ACT government has maintained that the legislation passed last year will provide Canberrans with a defence against those laws.
But federal Attorney-General Christian Porter said his legal advice had determined the defence wouldn't apply, and the ACT's cannabis laws "had not done what they [the ACT government] think it does".
Mr Porter has also made it clear he expects Commonwealth law to be enforced.
Prime Minister Scott Morrison also said he expected federal law enforcement agencies to enforce the law, while noting he supported the rights of states to make their own policies. The ACT is a territory.