Bruce Perens, the original author of BusyBox, commented in his blog about the recent wave of enforcement cases from SFLC. Perens was the original author of Busybox. The utility has morphed over the years, and the current authors claim Perens no longer has any copyright interest in it because none of his original code is in the code base — which Perens disputes. Perens is not party to the recent suits.
This points up a significant legal issue lurking in open source enforcement — the question of whether open source programs are joint works or multiple works of authorship. Rights in joint works can be enforced only with all the authors’ participation, whereas a quilt of individual works can be enforced by individual authors separately. This means serious potential problems for a defendant who must settle with a series of claimants rather than a single joint author group.
Also, even if no original code exists in a modified work, it can still be a derivative work, as every copyright lawyer knows. (Consider, for instance, a port into another language, or a rewrite using the identical structure, sequence, and organization.)
FSF generally takes the position that GPL covers an entire program as a single copyrightable work — if not, then its position on linking creating a single executable work would fall into question. But this position may contradict the idea that a program is a combination of multiple works, each of whose author has a separate right of action. This issue will likely become crucial one day in a GPL suit.
Please see my previous entry for the facts concerning the suits that were filed.