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Ratio vs Obiter: What they are and how to find them 🔎

If you’re new to studying law, or simply new to a common law legal system, you’re probably hearing the words ‘ratio’ and ‘obiter’ mentioned a lot. Both of these are found in legal judgments, and telling the difference between them can sometimes be tricky.


If that’s the case (get it?) for you, don’t worry! This post will help you understand the difference between the ratio decidendi and obiter dicta found in legal judgments. It’ll also give you some tips for spotting them in the cases you’re reading.

First of all, what is a ratio, and what is obiter?

What is a ratio?

What is obiter?

The ratio decidendi (plural: rationes) is the reason for a judge’s decision in a case. The ratio is the judge’s ruling on a point of law, and not just a statement of the law. Obiter dictum (plural: dicta) are legal principles or remarks made by judges that do not affect the outcome of the case. Obiter may help to illustrate a judge’s reasoning, but obiter is not necessary for the decision reached.

OK, got it, but how do I find them in a case?

Step 1: Understand what the legal issue(s) were in this case

In other words, what legal question were the parties asking the court to answer? Once you have a clear understanding of the issues in contention, it will be much easier to see what the different parts of the judgment are doing. For example, if part of the judgment is resolving the key legal issue through reasoning, that is likely to be the ratio. But if the judge suggests an imaginary scenario using different facts, this will not be the ratio because this digression is not necessary for the judge to reach their decision (but it may be obiter).

Step 2: Read the entire judgment

Sometimes the purpose of a particular part of the judgment will only become clear once you read it in context with the other parts. For example, a judge’s summary of the existing law (precedent) may look like the ratio until you read the next part, where the judge says that no existing precedent clearly applies to the case at hand!

Step 3: Look for the common characteristics

Although these attributes are not always determinative, rationes and obiter dicta have some common elements that are worth looking out for.

Common Elements of Rationes

Common Elements of Obiter

·  The judge is not merely stating the law, but applying it to the facts of the case (i.e. they are making a ruling on the case’s key legal issue(s))
·   The reasoning given is necessary to determine the outcome of the case (or: the outcome of the case would not make sense without this reasoning)
·  The legal statement or reasoning given is not necessary for the judge’s decision in this case (i.e. it does not affect the legal situation of the parties)
·  The legal statement or reasoning given is hypothetical (imaginary) and is introduced simply to illustrate or clarify something

But avoid these common misconceptions!


Keep in mind that not every statement of the law is a ratio. Judges will frequently refer to the decisions in previous cases. However, unless these decisions are endorsed by the judge(s) in this case, these statements of the law are not rationes.

A judge’s specific words (e.g. ‘in my opinion’) are not necessarily an indication of whether something is a ratio, or obiter.

Not all cases contain obiter! If you can’t find anything that looks like obiter, it may be because the case simply doesn’t contain any!