Hmmm. Did I mention the content of my prior post is not legal advice, and I vouch for none of it?
Copyright law is a little more complex than that rule of thumb, which doesn't appear to take into consideration the Copyright Act of 1976, and the Copyright Term Extension Act of 1998. Works older than 75 years can still be under copyright protection.
Quote:Before the act, copyright would last for the life of the author plus 50 years, or 75 years for a work of corporate authorship; the act extended these terms to life of the author plus 70 years and 95 years respectively. The act also affected copyright terms for copyrighted works published prior to January 1, 1978, increasing their term of protection by 20 years as well.
LINK
Additional Article.