http://www.copyright.gov/title17/92chap6.html#602
subsection 2 seems to be the defense for
allofmp3.com users
§ 602. Infringing importation of copies or
phonorecords
(a) Importation into the United States,
without the authority of the owner of
copyright under this title, of copies or
phonorecords of a work that have been
acquired outside the United States is an
infringement of the exclusive right to
distribute copies or phonorecords under
section 106, actionable under section 501.
This subsection does not apply to —
(1) importation of copies or phonorecords
under the authority or for the use of the
Government of the United States or of any
State or political subdivision of a State,
but not including copies or phonorecords for
use in schools, or copies of any audiovisual
work imported for purposes other than
archival use;
(2) importation, for the private use of the
importer and not for distribution, by any
person with respect to no more than one copy
or phonorecord of any one work at any one
time, or by any person arriving from outside
the United States with respect to copies or
phonorecords forming part of such person's
personal baggage; or
(3) importation by or for an organization
operated for scholarly, educational, or
religious purposes and not for private gain,
with respect to no more than one copy of an
audiovisual work solely for its archival
purposes, and no more than five copies or
phonorecords of any other work for its
library lending or archival purposes, unless
the importation of such copies or
phonorecords is part of an activity
consisting of systematic reproduction or
distribution, engaged in by such
organization in violation of the provisions
of section 108(g)(2).
(b) In a case where the making of the copies
or phonorecords would have constituted an
infringement of copyright if this title had
been applicable, their importation is
prohibited. In a case where the copies or
phonorecords were lawfully made, the United
States Customs Service has no authority to
prevent their importation unless the
provisions of section 601 are applicable. In
either case, the Secretary of the Treasury
is authorized to prescribe, by regulation, a
procedure under which any person claiming an
interest in the copyright in a particular
work may, upon payment of a specified fee,
be entitled to notification by the Customs
Service of the importation of articles that
appear to be copies or phonorecords of the
work.