A lot of LRH-issues are already in Public Domain
Here you will find the "Circular 3" by the Copyright-Office of the US-governmental Library of Congress related to copyright.
Basically it says this:
The Copyright Notice: Before March 1, 1989, the use of copyright notice was mandatory on all published works, and any work first published before that date should have carried a notice. For works first published on and after March 1, 1989, use of the copyright notice is optional. For more information about copyright notice, see Circular 3, Copyright Notices .
If you have a lot of old course packs you will find that HCOBs mostly were published without the copyright notice. This was at least true for the 1970s and before, which is most interesting to us, as these are the original LRH-issues of value for us.
Anything before 1989 published in this way is without doubt by international law in public domain.