Public domain is a work that is not protected by copyright. Once something is put into public domain it will never be able to be covered under copyright again. The book brings up the issue that Sonny Bono passed an act that was signed by former President Bill Clinton to extend copyright from 50 years to 70 years for an author or to 95 years for a corporation. Disney pushed Bono to pursue this act in order to save Mickey Mouse from going to public domain.
Once a work enters public domain it will remain there forever. With that being said that would mean that Mickey Mouse would be able to be reproduced however any user would like to distribute it. Laws are constantly changing but it seems that Disney influenced this Act in order to protect their Mickey Mouse.
This is yet another example as to why I think that once a work is obviously the work of a corporation it should be copyright protected till the end of the corporation plus 95 years. This will also help copyright laws to remain stagnant for a longer period of time.
Many people complain that they do not obey copyright laws because they are confusing and always changing so with something such as Mickey Mouse remaining in copyright that will help to alleviate any confusion and thus hopefully make people follow copyright laws better.