The Supreme Court recently put an end to Federal Circuit eff orts to revive a doctrine that prohibits patent licensees from challenging the validity of patents they have licensed. Although this doctrine of “licensee  estoppel” had been in something of a coma since the 1969 Supreme Court decision in Lear v. Adkins, it appeared that the Federal Circuit’s revival eff orts might nurse it back to health. Whether the Supreme Court’s recent decision in MedImmune v. Genentech is a temporary setback for the doctrine, or a binding “Do Not Resuscitate” order, remains to be seen....