In contrast to quarantining people who are known to be infected, I want to know how likely it is that, (for instance) California doesn’t allow people to enter and/or to leave, across her state borders.
Is there any precedent in US history for something like that?
(I would be glad to hear about historical cases or legal considerations, even if you don’t have a final view of the issue.)
The commerce clause gives the federal government broad powers to regulate interstate commerce, and in particular the the U.S. Secretary of Health and Human Services can exercise it to institute quarantine. https://cdc.gov/quarantine/aboutlawsregulationsquarantineisolation.html
Doing some research, thinking something like this might have happened during the migrations during the Dust Bowl, I found articles claiming that the LAPD attempted a blockade at the California border to prevent people entering the state who appeared not to have the means to support themselves using anti-vagrancy laws.
It seems that this drew a ruling from the Supreme Court stating that states could not restrict interstate migration (and presumably all movement). Source:
The result of this case was the following holding:
This ruling is rather limited and is specifically based on the idea that California had violated the “commerce clause” of the constitution. The concurrent opinions on the decision aimed for a more expansive justification. Wikipedia again:
However as I understand it since this was not the official finding of the court this does not constitute precedent; only the holding does.
Also note that this holding is specifically about states taking unilateral action to close their borders, and does not rule that the federal government could not do that. In fact I think it implies that it likely establishes that the federal government does have this power, though if they exercised it I expect it would be challenged on the grounds that even if the commerce clause grants this power the 14th amendment might supercede that.
As additional context, the United States effectively has internal external borders, i.e. the border patrol has checkpoints inside the borders of the United States to enforce the external borders by looking to catch people who have violated them. This is different but related and complicates the situation.
Also also, California seems, in my inexpert legal opinion, to violate this ruling in spirit if not in fact with its agricultural inspection stations, since it effectively restricts interstate commerce though not the movement of people.