I think legalizing Bitcoin is unique in every State or country of jurisdiction. Its process varies. But one thing is for sure, it is more complex than it was imagined. Why? It is because Bitcoin (or other cryptocurrencies alike) came to existence whereby it totally changes the fiat system. It does away with the norm as regards regular banks, government back ups, among others. In short, it is a class of its own. Moreover, it changes over time because day by day there are new developments that come with it making governments unable to come up or foresee substantial changes. To legalize it would be tantamount to carrying the burden of studying it and carefully foreseeing how it is going to be in the next days, weeks, months, or so.
I am sure this is where the bone of contention has always been as so many people will be looking for opportunity to invade tax. However, there is just no way can fiats be discarded and with the use of exchanges, the government can easily control the income tax issue without stress.
However, if anyone decides to do a P2P transaction to purchase some things, remember, tax with still at some point come to effect.