Cialis is not a controlled substance. I don't believe there are any "laws" that pertain, it just can't be sold as a substitute for the real thing. I've been getting it from various Indian pharmacies without any problems at all using e-check. They may delay at customs, and possibly check what's in the package, but it always arrives safely.
If if it was a controlled substance, for example anabolic steroids or opiates, they could punish you but it would have to be proven that you were breaking the law or intended to sell them. It is also pretty easy to get your pcp to give you a prescription for it so you'd be covered. I have a RX from my doctor that I don't fill in a US pharmacy. Why pay a $25 copay for 4 when you can get as many as 20 generics from a reputable foreign pharmacy for about the same price? For me, TRT has raised my libido immensely, but my erections only slightly. Makes no sense to me to have a high sex drive and to struggle to get it up.
You don't need a prescription to buy online, but if you are worried your MD should write you one, unless you don't have a problem with ED, and if you don't why even bother?