About: Penumbra (law)
In United States constitutional law, the penumbra includes a group of rights derived, by implication, from other rights explicitly protected in the Bill of Rights. These rights have been identified through a process of "reasoning-by-interpolation", where specific principles are recognized from "general idea[s]" that are explicitly expressed in other constitutional provisions. Although researchers have traced the origin of the term to the nineteenth century, the term first gained significant popular attention in 1965, when Justice William O. Douglas's majority opinion in Griswold v. Connecticut identified a right to privacy in the penumbra of the constitution.
