A "knock off" lure has to be changed a certain percentage from the original and you can get away with it. I don't remember the exact percentage but it is not that much. IF you come out with a "new" soft plastic lure design, you better have a war chest full of cash to defend it if the lure catches fish because it will be copied! Aw...the ethics of the bait business. Just look at what happened when the Chatterbait came out.