For an excellent view of just how crazy-complex copyright law in the U.S. is, take a look at this collapsible/expandable view of figuring out if a work is still under protection. Here's just a taste: 1951-1963: Was renewal filed during the “calendar year renewal window”? Then:
Copyright extended; with automatic extensions, protection will last until the December 31 of the year in which occurs the 95th anniversary of the original filing.
But if renewal was filed during the “anniversary year renewal window” (excluding dates also in “calendar year”), copyright is invalid.
In that the 1976 Act extended the first term to the December 31 of the 28th calendar year, any date up to but not including the December 31 of the 27th calendar year is too early to qualify as the last year of the first term.1964-77? That's a whole other (more complicated) matter. Think we maybe could use some Copyright Reform?