Declaring Bitcoins as currency is one thing. The other thing is how do people prove to the court that they don't own Bitcoins anymore because they've sent them

Declaring Bitcoins as currency is one thing. The other thing is how do people prove to the court that they don't own Bitcoins anymore because they've sent them to BTCST (the famous pirateat40 hedge fund), and even if judge accepts a blockchain transaction as actual evidence - that the receiving address actually belonged to BTCST. That will be fun to watch.