If Alan knows of some sites where copyrighted songs can be downloaded freely, and he sends the links to Betty, is this criminal?
Even if this is contributory copyright infringement, it is very unlikely to be criminal. The relevant US law is 17 USC 506. To be a crime, the act must be committed
for purposes of commercial advantage or private financial gain
and must consist of
the reproduction or distribution, including by electronic means, during any 180-day period, of 1 or more copies or phonorecords of 1 or more copyrighted works, which have a total retail value of more than $1,000;
the distribution of a work being prepared for commercial distribution, by making it available on a computer network accessible to members of the public, if such person knew or should have known that the work was intended for commercial distribution.
Simply sharing a web address does not fulfill either of these conditions. Moreover, as a practical matter, charges of criminal copyright infringement are only brought when infringing copies are made and/or distributed on a mass basis, as a business.
However, the act of sharing the address could constitute contributory infringement. Cornell's LII article on this states:
One who knowingly induces, causes or materially contributes to copyright infringement, by another but who has not committed or participated in the infringing acts themselves, may be held liable as a contributory infringer if they had knowledge, or reason to know, of the infringement. See, e.g., Metro-Goldwyn-Mayer Studios Inc. v. Grokster, Ltd., 545 U.S. 913 (2005); Sony Corp. v. Universal City Studios, Inc., 464 U.S. 417 (1984).
The Wikipedia article on this topic states (citations omitted):
The requirements for fulfilling the threshold of contributory infringement and imposing liability for copyright infringement on a party are:
- The defendant having knowledge of a direct infringement; and
- The defendant materially contributing to that infringement.
Material contribution is the second requirement of contributory infringement. For instance, merely providing facilities or the site for an infringement might amount to material contribution. But, some courts put emphasis on the contribution to be 'substantial' and therefore, would hold that providing equipment and facilities for infringement is not in itself determinative of material contribution.
The key US court case defining contributory infringement and holding that a contributory infringer may be liable is Gershwin Publishing Corp. v. Columbia Artists Management, Inc., 443 F.2d 1159 (2d Cir. 1971)
In that case, the firm Columbia Artists Management, Inc (CAMI) assisted various local organizations arranging or sponsoring community concerts, some of which were for profit, helped plan and arrange a concert at when a copyrighted song was performed without permission. CAMI knew that the song would be performed, and know or should have known that the song was protected by copyright and no permission was being sought.
The Second Circuit Court of Appeals held that CAMI was liable to the copyright owner for this infringement.
As such contributory infringement would be a tort, that is a cause for a civil suit, not a crime, any legal action would have to be taken by the copyright owner or the owner's agent. In the situation described inn the question, it might be doubted whether an owner would bring suit, and it is not clear whether merely providing a web address would constitute materiel assistance in committing infringement. Also, the owner would need to prove actual damages, or else rely on the statutory damages provided by 17 USC 504 (c). Under 17 USC 412 statutory damages are not available unless the work involved was registered with the copyright office before the infringement started, or within three months after the work was fist published. There are other limitations as well.