Let's say that there are 2 (hypothetical) countries with different copyright durations:
- Country A has a copyright duration of Life + 70 years.
- Country B has a copyright duration of Life + 50 years.
Country A does not apply the rule of the shorter term.
A work was published in Country B by an author who died 65 years ago. Let's call this the "original work." An adaptation (known as "derivative work" in the United States) of the original work was later published in Country B since the work is in the public domain. The author of this adaptation chose to license their work with a public-domain equivalent license (perhaps CC0).
My understanding of copyright is that it grants the author an exclusive right to distribute their work in whatever manner they'd like for some amount of time (determined by the copyright duration in a country).
Can a person in Country A legally use the adapted work? I'm assuming no, but then does that mean that the author of the work created in Country B does not technically have all the rights to the work they created, since they have no control over whether their work can be distributed in Country A? If that is the case, then would these rights be "granted" to the author of the adaptation when the copyright finally expires in Country A?