Yes.
This occurs due to the simple fact that bitcoin lacks a physical location. Therefore when one crosses a national border with capital controls, the movement or lack of of the bitcoin cannot be affected.
Another example is when a country, say Argentina, restricts the inflow and use of a substitute currency - like the US dollar. The BTC can be made illegal, but this is a different matter than restricting it's use.
Legal or illegal does not restrict black markets, rather they flourish where supply is lower than demand due to legal restrictions. Thus restrictions encourage black markets very existence.
I suspect this means that "making bitcoin illegal" will cause it to flourish in those countries which make it illegal, but nobody is really sure at this point. Kind of like Prohibition and the War on Drugs.....
