I don't know why that would be illegal. We tell people all the time how to understand patterns, etc. It's not copy right. I emb on it. First make sure you wash it a couple of times, it shrinks alot. There are alot of different stablizers out there so depending on what it is for back it and embroidery it. I can only think that it would cause problems if it was high density then you double up on stabilizers. I'm making double sided ones so if I emb on it for the babies, even though the stabilizer will be inside I'll use the no show mesh like you would for t-shirts because it'll stay soft.