They are simply means to implement them. [definitional]
Value judgments reflecting the views of advocates and judges form the critical decisional points in the law. Rules of logic do not make these decisions; they are simply means to implement them. When these judgments are made, the formal reasoning process sets in to test the validity of the propositions constituting the argument.
Ruggero J. Aldisert, Agatha D. Aldisert, Logic for Lawyers- A Guide …, loc. 95