After Sosa v. Alvarez-Machain, lawsuits against corporations under the Alien Tort Statute (ATS) have become the focus of human rights litigation. One of the most important legal issues in this area is how corporate aiding and abetting liability operates in lawsuits alleging violations of customary international law. Federal courts and legal commentators are split over whether federal common law can and should define the relevant standard for aiding and abetting liability. When recently confronted with the issue, the Supreme Court failed to muster a quorum. In the academic debate, Professor Steinhardt argues for the Modern position that federal common law is the appropriate source for secondary liability standards under the ATS. On the other side, Professors Bradley, Goldsmith, and Moore argue for the Revisionist position that established federal common law principles bar the creation of a corporate aiding and abetting liability. This Article evaluates the Revisionists� principles of federal common law. The Article argues that instead of barring the creation of corporate aiding and abetting liability, the Revisionists� limitations actually enable and encourage the creation and application of federal common law for ancillary issues, such as secondary liability, under the ATS.