US law doesn't determine anything as far as what a currency is an is not.by the definition of a currency it is one.
The state has to name something a currency. Sorry.
https://www.irs.gov/uac/newsroom/irs-virtual-currency-guidance
Also, bitcoin doesn't fulfill the requirements to be a currency (as it is usually defined). There are at least 3 big problems:
1) It's not commonly accepted and thus not easy to exchange (use).
I know you could argue with this and instantly give me 10 names of huge online stores that do, but that's not called "common acceptance". Try paying with BTC in a grocery store.
Far more sellers will accept a commodity like gold (and it doesn't make it a currency), many will prefer a simple barter.
2) Stemming from the above: BTC is not a stable store of value.
And I don't mean the (obvious) instability in time. I mean stability "in space", so to speak.
A widely accepted currency has similar value to everyone, but BTC doesn't. That is: if someone's needs are not covered by stores that accept BTC, he'll have to sell it to someone else first. And it might even be that he doesn't have a BTC wallet, so he'll have to create one. That's all additional cost, implying a lower value.
3) Bitcoin transactions are way to slow.
Blockchain is an excellent technology for things that today need long confirmation. For example if you're making a simple, ordinary bank transfer, it has to go through a very complicated system of confirmation and booking (it usually takes a day). Replacing that with bitcoin's 10 minutes would be a revolution.
But imagine paying with BTC in Walmart or for train tickets at the counter. That would be fun to watch.
I have done enough research into what bitcoin mining is and how it works and furthermore I am not mining bitcoin I am mining other cryptoCURRENCY.
So you've done research on how a bitcoin is created and maintained - the technical stuff. It has nothing to do with how money works. Learning how dollar banknotes are printed doesn't tell you anything about what USD currency is.
And the fact that it has a "currency" in name doesn't make it a currency. I mean, it could also be written like this: CRYPTocurrency. So what?
Bitcoin is legal tender in multiple countries
Bitcoin is legal in many countries, but it's not a
legal tender. I'm also including the wiki link (like
@FordGT90Concept did) in case you get bored with flashing mining BIOS etc.
Only the EU as far as I can tell. Most countries treat it as a commodity (including USA) and others explicitly declared it not "legal tender."
It's not a currency in EU as well. It's either a commodity or a unidentified object.
The wiki article you've linked only mentions a ruling by a Court of Justice of the European Union. Two issues:
1) it's not a court in a way you're used to. It's an institution that interprets Union's law and rules whether state legislation is in line with it. It never ruled that BTC is a currency, nor it has this kind of competence (since EU law doesn't precisely say what cryptocurrency is). Also, EU doesn't use a common law system (like US or UK), so a court ruling does not become a law rule (no precedent).
2) EU is not a federal union like US. EU legislation is not automatically in effect in all member states - they have very high autonomy. Even if EU decided to name Bitcoin a currency, it would take years for member states to accept it. In fact even euro - the official currency of EU - is a legal tender in just 19 out of 28 member states.