He said one, Meng could be extradited as the US has requested to face fraud charges, which he said would "not be a happy outcome; two, the USA might offer a resolution in the context of its own negotiations with China, or three, she could be released by a Canadian court".
The US Justice Department alleges that Meng was involved in violations of US sanctions against Iran. On Tuesday, he said she had "strong arguments" to avoid extradition in part because U.S. President Donald Trump had discussed the case.
Meng, chief financial officer of Chinese tech giant Huawei, was arrested by Canadian authorities acting on behalf of the United States in Vancouver on December 1. "It doesn't mean we will extradite her, but it means we have to detain her and have a hearing".
The Huawei case also has an economic dimension for Canada that has strained relations with the world's second-largest economy.
Days after Meng's arrest, Michael Spavor, a Canadian entrepreneur, and Michael Kovrig, a Canadian diplomat on leave, were arrested in China and accused of engaging in activities that endangered China's national security.
Meng's arrest has severely damaged ties between Ottowa and Beijing, which has demanded her immediate release.
Earlier Thursday, Prime Minister Justin Trudeau dismissed calls to remove McCallum from his post, saying such a change wouldn't help two Canadians detained by Chinese authorities get home sooner. "Maybe it's because Huawei is a national flagship company of China", he speculated.
The Canadian government has persistently pushed back at Chinese pressure over the arrest of Huawei executive Meng Wanzhou by insisting this is a rule-of-law country where the government can't influence judges. "Canada does not sign on to these Iran sanctions", he said.
After his remarks in his former riding were revealed to a broad Canadian audience, a storm of criticism erupted, primarily over McCallum's opining that Meng had "quite good" and "strong arguments" to win her fight against extradition.
Until now, the process has been carried out at arm's-length from politicians. "Certainly, Canada - through no choice of our own - is stuck in a dispute between the United States and China", he said.
Chinese Foreign Ministry spokeswoman Hua Chunying said Thursday the case against Meng had "never been a normal legal case".
Ever since Canadian law enforcement detained Meng in early December on a USA extradition request, the Liberal government has maintained that Canada was simply following the rule of law by adhering to its commitments outlined in the extradition treaty it has with the U.S.
The Chinese government has repeatedly and furiously called for her release, labeling the charges political.
Experts said that while McCallum's remarks might have been controversial on the surface, the substance of his legal analysis was not far off the mark.
"President Xi Jinping was very angry about this and so others in the Chinese government have taken the lead from him", McCallum said.