Legal terms have settled meaning in the core and debatable meaning in the penumbra.

Evidence

More commonly, however, the indeterminacy to be filled by a decisionmaker’s choice is not pervasive throughout the range of applications of a term. Instead, the indeterminacy is encountered only at the edges of a term’s meaning. As H.L.A. Hart tells us, legal terms possess a core of settled meaning and a penumbra of debatable meaning. — Frederick Schauer, Formalism, 37

Categorization

• DEFINE: Defines Hart’s core/penumbra distinction, foundational to the book’s subject.
• XREF: Connects to Hart’s The Concept of Law and standard jurisprudence texts.