A warrant canary is utterly useless as a defense.
Any secret legal order to alter IT systems (the specific threat model it is most often suggested for) can logically also include an order to maintain a fake warrant canary.
Part of the theory of a warrant canary is that compelled speech (and in particular a compelled lie) may be easier to challenge than suppressed speech. While that isn't definitive, there's some jurisprudence to back that theory. If you have a warrant canary, you should be prepared to challenge any such order in court and use that as the defense.
An important detail in the US juristiction certainly.
On a practical basis i cannot evaluate the jurisprudence involved and I would assume the number of people who credibly can is very small, especially in the context of "secret courts for national security reasons".
A useful test would be if any of those few had demonstrated a personal risk using this as a defense and succeeded.
The rest of us can only guess the risk based on the reputation of the entites involved.
How so? Censorship is explicitly forbidden by the US constitution, and even so it happens (in this case, "in the name of national security" or whatever).
The current interpretation says there are certain reasonable restrictions on the 1st for the public safety. Compelled speech isn't accepted as constitutional.
Remember the constitution only really, effectively, says whatever the current Supreme Court says it means. And really I don't think anyone want's the 100% literal 'shall make no law' interpretation of free speech; that would throw out any kind of labeling laws for starters, companies would have no government compulsion to accurately label drugs or food products for example.
is ordering silence and secretly seizing control of the publication technology (ie website) then maintaining a false warrant canary a way around compelled speech ?
if so then regular live press-conference/video appearances would be the only practical implementation method.
if they say nothing and exit then the canary is dead.
It could be, I'm not a lawyer. That seizure would be something you could fight in court too on two fronts: seizure of property and if the government takes over your means of communication and pretends to be you what separates that from directly compelling speech.
You threaten that and they say “go pound sand in the courts”. And even if you “win” in the courts you still lose because “the process is the punishment”.
