You can read HDTT's position on US copyright law here:
http://www.highdeftapetransfers.com/page/7/faq.phpThey or their lawyers seem to believe that when considering recordings made before 1972, only the original masters are afforded copyright protection; that the commercial releases of those recordings, whether LP, quarter-track tape, or CD, are not eligible for protection under US copyright law. This certainly seems at odds with the way others have interpreted the law, and I seem to recall a recent case involving Naxos that would call their interpretation into question. Anyway, it'll be interesting to follow the matter as it unfolds.
HDTT appear to have removed the items in question from their website, so perhaps they're rethinking their position.
James