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.
All rights were written, in English, and mean what they said.
The penumbra gave us the right to kill a baby, but not to keep our home safe from search and steal by the gummint agents.