Another issue for open source and free software licenses is their enforcement in jurisdictions outside the United States. The global nature of commerce and the generally free travel of software across national boundaries implicates the enforcement of open source and free software licenses in a number of jurisdictions, not only those in the United States.
International enforcement of copyright laws is frequently lax. While many countries are signatories of treaties that provide for the international enforcement of copyright protection (such as the Berne Convention), such treaties are frequently disregarded. The proliferation of "pirated" DVDs and CDs is a testament to that. The use of file-sharing software frustrates enforcement of copyright even within the United States. Within such a framework, it may seem impossible to enforce the terms of open source and free software licenses, which depend, as just noted, on the foundations of copyright for enforcement across national boundaries.
In many countries, particularly in the "developed" world where most software creation takes place, the enforcement of copyright is routine. While the unauthorized distribution of copyrighted material is commonplace, it is nonetheless difficult for any established company or person to reasonably hope to profit from the illegal distribution of copyrighted material. This is particularly true of software. Users of software, at least commercial users, are generally more concerned with reliable performance and support than with the incremental cost of software. Users expect to be able to rely on a software maker's products and to receive support for that software's application going forward. Providing this reliability and these services requires the existence of a stable, aboveground organization exactly the kind of organization that is subject to suit and accordingly to the legal enforcement of copyright law.
The question thus becomes whether open source and free software licenses can reasonably be expected to be enforced, as a legal matter, outside the United States. The answer to this question is a slightly qualified yes. Many countries are signatories to the Berne Convention, which provides for copyright protection more stringent in many respects than that provided by United States copyright law. Moreover, as has been the case with the enforcement of proprietary licenses, the existence of some amount of "pirating" or distribution outside the boundaries of a given license, such as with the unauthorized distribution of music, is not fatal to the successful distribution of the licensed work. Even if a certain, substantial, percentage of distribution of work is through illegal channels, the machinery distributing that work is still capable of thriving, creating, modifying, and delivering new work.
This is likely to be particularly the case with open source and free software licensed work, for the reasons already discussed. "Pirating" work generally means nothing more than the distribution of the work itself without the payment of royalties (or other applicable forms of payment) to the creator of the work. "Pirating," in this sense, thus does not violate the restrictions applicable to most open source and free software licenses, which generally do not limit the free (i.e., without charge) distribution of unmodified versions. Only the distribution of modified work in a way inconsistent with the terms of the applicable license really "counts" as a violation of the license.
"Pirating" in this sense is also limited by the fact that the major markets in which software or any other kind of work can be sold at a profit are subject to legal constraints and the enforcement of law. In addition, practical constraints are more likely to limit the extent of such piracy with regards to software than with regards to other forms of expression, such as CDs or DVDs. While a consumer may be willing to take a chance on a five dollar bootleg CD or DVD that she intends to use just for her personal entertainment, such a consumer is much less likely to take such a chance on software, the stability and functionality of which she really must rely on.
These dynamics probably explain the relatively small amount of litigation spawned by open source and free software licenses. While these licenses certainly can be (and are) infringed upon, market forces and social dynamics tend to limit the extent of such infringement, even in the absence of vigorous legal enforcement of the license by the licensor.