Ratio Decidendi
[It is] as well to create good precedents as to follow them.
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Introduction
In the course of deciding cases courts make law in two ways. Cases make
common law; this law is sometimes referred
to as rules,
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principles or
doctrines.
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Cases also interpret both common law and statute law.
As the court makes this law it states the relevant rule in the judgment. This
principle of law will decide the case one way of the other, that is, in favour of
the plaintiff or the defendant. This principle is called the ratio decidendi,
meaning literally the reason for the decision.
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It is so called because it is the
reason that the decision was made one way rather than another.
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As Lord
Campbell succinctly put it the ratio is “the rule propounded and acted upon in
giving judgment”.
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It will usually be obvious, in broad terms at least, what
this rule is. In the best case (which arguably should be the common standard)
the ratio is explicitly stated in the case by
the court. In any event it can be
identified by the fact that, since the rule was in issue, it will have been argued in
the proceedings.
Making Common Law
In termes hadde he caas and doomes alle,
That from the tyme of kyng William were falle.
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If the court is making a new common law rule (a rare event these days), the
ratio will naturally be the common law rule so made. Understanding the
process by which common law is made enables a lawyer to identify the ratio
of a case that has made common law. This process is explained by the model
for forming law. Since most of this has been explained in earlier discussion a
summary will now suffice.
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Sir Francis Bacon
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Schauer (1991)
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Rubin and Feeley (1996)
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For discussion of how to find it see Goodhart (1930), Goodhart (1959). See
also Cross (1997A). However, this text takes a different approach as explained in
this chapter.
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Jaconnelli (1985). To clarify this point, as the reason for the court deciding
the case one way rather than another, the ratio decidendi is the legal rule that the
court formulates then applies to determine the case. It is necessary to distinguish
‘reason’ in this sense from the policy or other reasons that the court used in
formulating this rule.
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Attorney General v Dean and Canons of Windsor (1860) 8 HLC 369, 392; 11 ER
472
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Geoffrey Chaucer The Canterbury Tales, describing the Serjeant.
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Chapter 7 Common Law Rules
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