Even the vodafone case was decided in favor of Vodafone. Secondly, even if VAT or any other tax is imposed restrospectively (very remote chance) even then the issue of incarceration will not come into effect. Also, if these kind of regulation comes further a timeline will be provided to the traders to pay the taxes without any interest or penalty.
Hope the answer clarifies the doubts in your mind.
I think we are talking about 2 different things. The retrospective law was passed
after an existing case was decided in favour of Vodafone. People may not be worried about incarceration, but they could still be concerned about excessive taxes. Excessive taxes (imposed retrospectively) would effectively result in the government seizing your bitcoins (as taxes).
