Summing up cannabis laws in the United States is nearly impossible. Just to give the gist of the complicated laws across the nation requires a map with six different color coded categories. And even that map ignores two basic facts about marijuana law. The first is that it’s almost all still technically illegal according to federal controlled substance provisions. The second is that there is still one variety of cannabis product that is legal in every state.

CBD oil is not illegal under federal law, but only in a very specific circumstance: that it is derived outside the country from hemp stalks and not from flowers. Motherboard recently talked with Michael Chernis, attorney and founder of Chernis Law Group. Chernis said that “if we’re talking about the federal legality of a CBD product, it depends on where it derives from… [The] legality of a product containing CBD depends on the plant material from which it was derived, and not its percentage of THC.”

Since this kind of CBD extract isn’t policed by federal drug laws, the FDA is the government agency that should be in charge of regulating it. But the FDA only regulates CBD extracted from hemp as a dietary supplement, which means it isn’t authorized to qualify the safety or effectiveness of these products before they go on the shelf.

That means that the legal CBD extract market is not set up to serve medical marijuana patients with any kind of standard of quality. By contrast to the heavily regulated medical marijuana markets in many states, hemp-based CBD is often significantly lower in medical benefit. While the FDA doesn’t take these CBD “dietary supplements” off the shelf, it did issue a warning to consumers that some of the products marketed as CBD oil didn’t even contain any of the medicinal cannabinoid and that buyers “should beware purchasing and using any such products.”

Furthermore, CBD derived from hemp stalks is often less healthy than that extracted from cannabis flower. Hemp-based CBD is missing some of the key cannabinoids and terpenes that make CBD medically effective, according to the entourage effect. In addition, hemp is a “bio-accumulator” that absorbs toxins from the soil, according to Project CBD.

So, until federal laws change, medical marijuana patients who want to stay within the law will be forced to consider subpar and possibly even harmful products like CBD dietary supplements. Or they’ll have to move to California, where medical marijuana is not only plentiful but tax free for the next year too.