Hywel studied the English legal system and reformed Welsh law in his own realms (later called the Cyfraith Hywel or "Laws of Hywel"), and when he went on pilgrimage to Rome in 928, he took his collection of laws, which allegedly were blessed by the pope.
Hywel studederede det engelsk lovsystem og reformerede walisisk lov i sine gamle kongeriger (senere kaldet Cyfraith Hywel eller "Hywels love"), og da han tog på pilgrimsrejse til Rom i 928, medbragte han sin lovsamling, som efter sigende blev velsignet af paven.