(Link to studies re: teaching about this? & Bring up real gravity (and stupidity of “no copyright intended”), but also balance of teaching things in a day-to-day useful way.
“In the U.S. copyright law is simpler.”
“a court” –> rather, ask a librarian if they would back you, should it come to that.
However, authors may easily change or update this status at any time to “some rights reserved.”
Comes across as normative (which is fine, given the legal and ethical gravity), but possibly a bit heavy-handed.
[May be helpful to make explicit that it can’t go back the other way. Also, creative commons is explicitly re: having a human-readable version in addition to the legalese.]