There goes Gibson being bullies again. I believe there’s a statue of limitations involving patent expirations for electronic circuits but I guess instrument body shape patents are exempt from this somehow?
It's the difference between patents, copyrights and trademarks.
A patent applies to inventions, and gives the owner 20 years of exclusive rights to the invention before it enters the public domain.
A copyright applies to a creative work, and gives the owner exclusive rights to publish/perform until a given period after the creator's death before it enters the public domain.
A trademark applies to any design that identifies a business, and gives the owner exclusive rights to it indefinitely, but the trademark will lapse if unused or unprotected.
Patents and copyrights exist to protect the people who created something and let them profit from their creations before letting the public own them. Disney is infamous for their influence on copyright law, since as soon as Steamboat Willy falls into public domain Mickey Mouse becomes a public domain character. But in concept the understanding is that eventually these things just become a part of the public fabric, and are bigger than their creators.
Trademarks are a different beast. If they aren't protected then they lapse completely. That's why Gibson is going after Dean, if they don't they run the risk of losing exclusive rights to the Explorer and Flying V shapes (but
not the names, because those are their own trademarks and they aren't being challenged), and if that happens then anybody can and will make them. For example, ESP would be able to make Gibson-accurate Explorers and Flying Vs as Hetfield signature models.