Chapter — Slater, Manual of Moral Theology
Chapter IX. The Cessation of Law
A LAW may cease to bind in various ways. It may be abrogated or altogether withdrawn by the legislator, or his successor, or his superior. For he who made the law can unmake it. Derogation is the annulling of some portion of the law, while the rest remains intact. The law may fall into desuetude from non-observance, or on account of a contrary custom being introduced. It may also cease to bind because it no longer attains the purpose for which it was made, and has become useless. It may cease to bind in particular cases because a dispensation has been obtained. Something must be said on custom, on a law becoming useless, and on dispensations, This will be done in the three following sections.
p. i, 67