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How to Find the Ratio Decidendi

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Finding the ratio decidendi of a case has to be one of the trickiest skills to master at law school. Lecturers explain that ratio is the rationale for the decision, but when you’re at home trying to write a case note, it can feel like ratio decidendi is really Latin for “good luck with that”.

Here are some tips for tracking down that elusive ratio…

1. Look at your Subject Outline, Reading List or Case List

Take a peek at the topic headings, cases and journal articles listed above and below the case you’re about to read. Doing this before you start reading the case will help to provide some context for your search for the ratio and help you to avoid getting sidetracked by all that obiter.

2. Read the Headnote

Chief Justice Gleeson once said that, “There are some cases where people who write headnotes deserve a medal”, and he was right. When you start reading the judgment, begin with the headnote – this will highlight the key issues or legal principles considered by the case.

3. Read the Whole Case

The ratio normally appears towards the end of a judgment, but unfortunately you can’t just skip to the end. It’s a bit like watching a mystery show; it’s harder to find the answer when you jump in part way through, so you’ll have to read the case in full.

In its most basic format, a judgment starts by outlining the facts of the case, before considering the legal arguments presented to the court, and then making the decision.

The ratio won’t be in the summary of the facts at the beginning but you do need to read the facts as the court’s decision on how the law applies may rest on some of the parties’ circumstances. The court’s analysis of the legal arguments is also essential reading, although the ratio will probably be located at the end of the legal analysis, just before the court makes its finding that the defendant is guilty, or the defendant was negligent, etc.

4. Focus on Key Facts and Arguments

To help you find the ratio, when you’re reading the judgment, focus your attention on the precedents or legal principles the court discusses at length, and the facts of the case that the judges emphasise.

5. The ‘Aha!’ Moment

The ratio is essentially the reason why the court reached a particular decision. The outcome of the case therefore depends on the ratio decidendi, so if you read something that makes you think you know which party is going to win (or lose) you may be in ratio territory. Going back to the crime show example, it’s a bit like watching a murder mystery and having a hunch as to whodunnit.

6. Dealing with Multiple Judgments

If you’ve got a High Court decision where some of the judges have written a separate opinion, you know that the ratio won’t be lurking in the dissenting judgment, instead look for the ratio in the majority decision.

But if each judge wrote a separate decision, your hunt for the ratio probably just got even trickier. If many of the judges agreed or were close enough in their view of the key legal principle(s), you may be able to distill a ratio, or at least a sort-of ratio if there were some small differences in opinion. If the majority agrees on the outcome of the case but took completely different views of the law to get there, you might not be able to find a ratio.

7. Don’t panic if you can’t find the ratio

It’s okay if you can’t find the ratio; lots of law students, and even lawyers and lecturers can have difficulty with this, particularly in older cases where the ratio is sometimes hard to distinguish from the obiter.

If you find yourself in this situation, look the case up in your textbook, casebook or lecture slides – there’s a very good chance that the ratio decidendi will be explained, if not actually quoted, in the case summary. Even if you think you’ve found the ratio, this can be a good way to confirm that your approach is working.

FROM THE ARCHIVES: This story was first published on Survive Law on 23 September 2013.

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