Nobody has the authority to regulate Bitcoin

[Thanatopsis]

Businesses accepting Bitcoin, no matter if they are exchanges or simply merchants, are already being regulated by the US.

All businesses in the US have to follow FinCen Money Laundering regulation and some of them fall under their definition of money transmitting businesses. That is the reason why there is no big public exchange in the US right now. So yes, the Fed (currently) has no authorityto regulate Bitcoin but she also said that

FinCEN has indicated that current money laundering statutes are “adequate to meet enforcement needs”.

Which means they are happy with the current state of their regulation and any Bitcoin business better be prepared to follow AML and KYC regulation to the letter. Especially if you qualify as a money transmitter, which by the way is pretty easy to do. Just buy and sell bitcoin on localbitcoins and bam you are a money transmitter. If you don't believe me, ask those guys in Florida that were arrested for being part of a money laundering scheme.

regarding taxes, the IRS is not going to let people flagrantly evade taxes using Bitcoins. At least not for long. They will think of something. maybe they will simply require all bitcoin business to collect 10% taxes on every transaction. You can then go to the IRS and prove to them that your Bitcoin holdings are open, transparent and taxed and get your 10% back. A withholding tax to ensure tax compliance would not be unheard of. And you better believe merchants are going to comply if the alternative is a nice stint in federal prison for tax evasion.

[FreedomFeens]

Nobody has the authority to:

steal your money at gunpoint to fund their arbitrary whims
force you into their contract before you are able to consent
force their will upon you up to the point of death/beating/caging for non-crimes
claim ownership of your body and your possessions

But they do it anyway.  To think they wouldn't claim ownership of bitcoin is absurd given the lines they have already crossed.

[studio1one]

#Eric Cartman does.

[marcotheminer]

Governments can't regulate bitcoin transactions, but they can regulate businesses, and tax goods.
Transactions will be harder to trace, but once you have matched one address to a person, you can easily identify contact addresses.
Some taxes will be harder or impossible to collect, like tax for property, inheritance, large gifts etc. It will still be possible to catch tax dodgers when they screw something up though.

which in turn will slowly kill bitcoin even if its not directly regulated.