The Blocking Effect is produced by the Elsewhere Condition (henceforth EC; [Kiparsky, Paul, 1982, “Lexical phonology and morphology”, Linguistic Society of Korea, p. 8]), which enforces disjunctive ordering among competing rules that have different degrees of generality: (2) "Elsewhere Condition" Rules A, B apply disjunctively to a form Φ iff: (i) SDA is a proper subset of SDB; and (ii) SCA is distinct from SCB. In that case rule A, applying first, blocks rule B.
- Giegerich (2004), Pag. 192