Its the annotated codebooks that are copyrighted. The stuff that comes from the Queen's Printers isn't copyright. If you add annotations to a Bible, you can copyright the final work. But a KJV or Douay Rheims is public domain sans annotations.

Re: Court buildings
Yes sometimes governments lease space from private persons. They don't always own the entire buildings. Even if that is the case, the easement and access to the premises remains public during their business hours.