Justice Stevens' Sony opinion discusses in some detail how patent law's "staple article of commerce" doctrine will be imported into copyright. The Grokster decision purports to import the active inducement standard from patent law, too. But it's unclear whether the Court actually has done so.
First, patent law requires a causal connection between the inducer and direct infringer. The inducement has to have actually influenced someone to commit an infringement. A court reading Grokster may be tempted to conclude, however, that a mere intent to encourage people to infringe may be enough. In particular, the Court focused on the P2P companies' decision to attract Napster users, without pointing to any evidence that Napster users actually migrated to either the Grokster or Morpheus systems.
Second, patent inducement has never taken failure to stop infringement or inaction as relevant to inducement. Instead, patent inducement requires "active" steps to specifically encourage infringement. Yet, a court might rule otherwise in the copyright context, as the Court today pointed to the P2P companies' failure to redesign their networks as relevant in light of initial evidence of intent to induce.
Third, patent inducement has not treated infringement's relationship to a company's business model as relevant. Again, the Court took this factor into account in light of other evidence of inducement.
A straightforward transplant of the patent inducement doctrine might have provided technologists with some insight into what it will mean for them in the copyright context. Unfortunately, the Court's decision muddies the import of patent caselaw.