John Mark Ockerbloom
Apr. 11, 2006
What’s in the public domain?
•Anything copyrighted before 1923
•Anything that’s specifically dedicated
–E.g. fed. gov. docs in US; small amounts of private stuff 
•Anything that didn’t “maintain” copyright as was once required:
–Copyrights before 1964 that were not renewed (most weren’t)
»But many of most significant books were renewed
»(note also some may contain separately renewed material)
–Publications before 1989 w/o copyright notice
»(Inadvertent omissions after 1977 sometimes fixable)
–But: Many foreign works were retroactively exempted from maintenance requirements in 1996
»Key requirement: First foreign publication needs to be more than 30 days before first US publication to get exemption
Renewal after 28 years

Less than 15% of all copyrights, 7% of book copyrights (Copyright Office, 1961); less than 10% of book copyrights 1923-1963 (Michael Lesk via Denise Troll Covey)