I don't think the US is at the point where they torture citizens for private keys. And they'd only be able to use jail as leverage by offering a reduced sentence. Even then, you might refuse if, for example, you'd rather stay in prison and leave the money to your family.
Be careful with your first sentence. For example, the US would not hesitate to torture Snowden for his key if they even had the slightest way to get their hands on him.
Just declare this person an enemy of the state/terrorist and there you go - to you and your encryption.
Even then, you might refuse if, for example, you'd rather stay in prison and leave the money to your family.
Somehow, I don't think the government will leave you that option ;) You'll stay in prison and have the means to use the bitcoins confiscated or outlawed. They can also confiscate all your other assets, like the house your family lives in.
There are many options available to a sovereign government which mean that relying on purely technical measures will not defeat them, because they have a monopoly on force, up to and including lethal force.
Yes, but unless the government becomes significantly more tyrannical than they are at present, bitcoin is a useful tool for dodging asset forfeiture. For example, your private keys could be distributed amongst n of m gangsters/wife/sons/lawyers/whatever including foreigners.
Implemented correctly, it's much much more difficult to steal or seize than cash while at the same time being much much easier to smuggle to places with no extradition where money trumps the rule of law.
