Copyrights are a huge deal in the embroidery world. When I first started out someone sent me a bunch of tree and leaf designs. They were so cool and if anyone asked I passed them along. I found out later they were from a Brother card and here I was sharing. We even had people trolling on the different embroidery groups trying to get you to send them designs, and then bang down came the hammer. Rumor had it that a couple in Canada lost everything, machines, $, and even the right to embroider anymore. Hopefully a rumor, but these copyright cops, could be vicious. They were mostly connected to a certain big design company. I made sure I never bought any of their designs, ever. I just try and respect the designers creation.
Hetty G gave us some great info, but she does state you can't copyright an idea. Well, one designer made these shadow applique designs and copy righted them. They have been in the public domain for hundreds of years, but I suppose not by machine and she took them and has a patent on them now. Not sure if that is the same thing.
I think the golden rule applies very well here.