To make a common law rule in the most rational way a court would canvass in
an exhaustive way various versions of the
rule then choose the best.
362
In
practice, a court will often just make the new rule, with little contemplation of
alternatives.
To make the common law rule the court does three things. First, the court
identifies the material facts, which consist of the facts that mark out the case
for legal regulation. For example, if the court is making a new cause of action,
it has to identify the wrong conduct for which it wishes to provide a remedy.
These material facts can be labelled Facts 1-n. Second, the court generalises
each material fact to some degree to formulate the elements of the rule, these
elements being labelled Elements 1-n. Thus Fact 1 is generalised to form
Element 1, Fact 2 is generalised to form Element 2 and so on. In short, Facts
1-n are generalised to form Elements 1-n. Third, the court has to determine the
consequences of the rule.
If the court does decide to canvass alternative versions of the rule, it first of all
formulates these versions. One version of a rule can differ from another
version in any of three ways that correspond to three processes in making the
rule –
they can differ in the choice of material facts, the degree to which a
material fact is generalised and the formulation of consequences. Once these
versions are formulated, the court should try to predict the effect of each
version and calculate their respective net benefits. Then it identifies the version
which yields the highest net benefit. This is the version of the rule that it should
bring into law.
When making a new common law rule a court logically should be guided only
by policy
363
because there is no other rational way to proceed.
364
In practice,
however, a court will often refer to prior cases when making a new rule.
365
This can be justified when it involves arguing policy by analogy. An
established rule applies in situation X and the situation before the court is
similar to X. Consequently the court adapts the policy underlying the
established rule to create a new rule.
366
In the process described so far, the court is making
a common law rule that
fits the facts of the case, since the elements of the rule are formulated by
generalising the material facts of the case. However, there are two other
362
Chapter 7 Common Law Rules
363
Chapter 12 Policy
364
Christopher Enright Legal Reasoning Chapter 10 Policy
365
It
may be, too, that a court seeks to obtain consensus, which then becomes
one of the decision making criteria – see McKinley (1987).
366
Christopher Enright Legal Reasoning Chapter 8 Analogy
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