Robert Spoo has an interesting theory on Ulysses
copyright in the US: Ulysses lacks a US copyright
and is therefore in the public domain. So while
people in Dublin will be unable to utter words
from Joyce’s works this Bloomsday, Americans
can have at it.

Here’s an excerpt:

Under that law (U.S. copyright law in force
in 1922), Joyce would have had to deposit
a copy of the book at the copyright office
within two months of publication in France,
and then, within another four months, have
the book printed on American soil by a U.S.
printer. Spoo says Joyce did not meet these
requirements, thus relinquishing his novel to
the public domain. It was transformed from a
private monopoly into a public resource, and
the benefits once enjoyed by the creator passed
to the user.

......He points out that in a sworn deposition in
Paris in a case involving an American publisher
who had printed a pirated version of Ulysses
in 1926, Joyce was asked if he had ever tried to
secure an American copyright. Spoo said Joyce
answered under oath that he had not.”