It is not against the law in most places. There are individual sites that demand it, pretty much all dive operators require it, and dive shops will want to see a card before filling a tank. If you can find a way to get your tanks filled and either dive from shore or your own boat, you can get away with it forever.I wonder though, there are a couple students who have been diving for years in my class. Were they just illegally diving this whole time? Is it really a huge problem to dive without being certified? I know it's not smart and potentially very dangerous if you have not been taught safety techniques but logistically how much of a problem could it be?
But anyone who is certified and helps an uncertified diver do those dives is taking a liability risk. The odds are pretty strong that nothing will happen and everything will be fine. But my recent experience with that lawsuit I mentioned tells me to be ultra-careful.
Kelemvor's suggestion is a good one. If I were in the area and you were willing to pay a very small fee and sign a liability waiver, I would do a Discover Scuba session (or more) with you.