Oh .... perhaps I was thinking of the movie business .... I read that stuff there that's over 10 years old automatically enters public domain for ownership of rights.
I do know that an invention, once patented, can have it's patent duration extended if the patent owner files a new patent with significant advancements/additions to their product.
Also, a funny side detail ... the Copyright Protection Act (signed in Stockholm, 1978) ... an excerpt of it is shown in the beginning of every commercially made VHS tape and DVD sold in America ....
What Hollywood never shows is the expiration date... December 31st, 1999.
This is why former President Bill Clinton signed into law the Digital Copyright Millennium Act, which gives the end consumer MUCH more power over things that they have purchased... but Hollywood doesn't want us to know about that.
Downloading is not a crime. The Supreme Court of the United States of America ruled that downloading copyrighted materials is never a crime. Uploading it is the crime ....
Hollywood makes it's living lying to the world and making us believe it ... why would this be any different?