Ratio Decidendi vs Obiter Dicta: What’s the Difference?
Learn the difference between ratio decidendi and obiter dicta in A Level Law, including which part of a judgment binds later courts and a clear example.
Ratio decidendi is the legal reason necessary for a court’s decision. Obiter dicta are comments in a judgment that are not necessary for that decision. The key difference is that the ratio can bind later courts under judicial precedent, while obiter dicta are not binding, though they may be persuasive.
How does this work?
A judgment explains a judge’s decision. Its ratio decidendi (often shortened to ratio) is the rule of law the judge applied to the material facts: the facts that mattered to the outcome. A later court deciding a case with sufficiently similar material facts may have to follow that rule, depending on the position of each court in the court hierarchy. This is a binding precedent.
Obiter dicta (often shortened to obiter) means remarks made “by the way”. A judge might discuss what would happen if the facts were different, or give an opinion on a legal issue that does not need to be resolved to decide the case. A later judge may find those remarks helpful, but does not have to follow them merely because they appear in the earlier judgment.
A simple example
Suppose a court decides that a shop breached a duty because it failed to clean up a spill it knew about, causing a customer to slip. The legal reason needed to reach that decision forms the ratio. If the judge adds, “The result might be different if the spill had happened only seconds earlier,” that comment is obiter: the court did not need to decide that different situation.
Exam mistake to avoid: do not treat every sentence in a judgment as binding. Ask which legal reasoning was necessary to decide the case on its material facts. Also, do not dismiss obiter dicta as irrelevant: they can influence later decisions even though they are not binding.
