BC should do this—as Atlantic Canada has—and it is fully legal. I will explain why in this thread. https://www.theglobeandmail.com/canada/british-columbia/article-bc-is-seeking-legal-advice-on-limiting-interprovincial-travel-horgan/

First, the right to mobility in s. 6 of the Charter covers just two specific instances: taking up a residence, and gaining a livelihood. Casual travellers have no right to mobility to speak of.

Second, even in those two covered instances, the right is subject to “any laws or practices of general application in force in a province”, such as for public health protection, as long as it is non-discriminatory.

Third, the s. 6 right already has a health-related exemption written into it, and most Canadians know about it: the waiting period (usually 3 months) before being eligible for public health insurance in a new province of residence.

Fourth, if carving out an exception for health insurance routinely is allowed, almost certainly carving out likewise for public health protection in times of COVID is allowed.

Fifth, the power of quarantine is already exercised validly by provinces in their territory. The constitution allows that under the “double aspect” doctrine, even though “Quarantine” is a designated federal power in s. 91 of the 1867 constitution.

Sixth, Newfoundland’s border measures were already challenged in court—and they survived.

Seventh, the pandemic is not a fact pattern where judges are are likely to rebuke the government. Extreme necessity begets deference, and if BC tries a reasonable border closure law, it will survive court challenges. I’d say 95% likely, as a guess. *end*