Owning Bitcoin and trading in Bitcoin for anything (goods or other currency) are legal as far as we know. Unless you own a business dealing with Bitcoin, all you need to do to be legal is add the profits that you make to your income. That's all. I'm not sure about the tax rules when you have a business in Bitcoin, but it's still legal to do anything with it.
Owning Bitcoin and trading in Bitcoin for anything (goods or other currency) are legal as far as we know. Unless you own a business dealing with Bitcoin, all you need to do to be legal is add the profits that you make to your income. That's all. I'm not sure about the tax rules when you have a business in Bitcoin, but it's still legal to do anything with it.