LAW5000 · Australian Legal Reasoning and Methods
Case Law & Precedent I
Topic 2 introduces the doctrine of precedent (stare decisis) and the skill of separating the ratio decidendi — the binding rule — from obiter dicta. You learn to isolate the material facts that drive a decision and to tell binding precedent from merely persuasive precedent using the court hierarchy. This is the analytical spine of the unit: every case brief, problem answer and the case note in the 30% Research Assignment depends on getting the ratio right.
What this chapter covers
- 01Stare decisis: why courts follow earlier decisions — coherence, justice, certainty, efficiency, equality
- 02Ratio decidendi (the binding rule) vs obiter dicta (persuasive remarks 'by the way')
- 03Identifying material facts — the 'would the outcome change if this fact were removed?' test
- 04The taught shorthand: material facts + legal issue = ratio decidendi
- 05Binding vs persuasive precedent, and the role of the court hierarchy (vertical operation)
- 06Difficulties in finding the ratio: stated at different levels of generality, no clear majority, ratio blurred with obiter
- 07Latin vocabulary: ratio decidendi, stare decisis, obiter dicta
- 08Judicial independence: appointment, and removal only for proved misbehaviour or incapacity (s 72 Constitution)
Isolating the ratio from obiter dicta
- +1Material facts. Pin down the facts crucial to the outcome: the retailer placed goods within a customer's reach, and the goods were unsafe to handle (the bottle exploded on being lifted). Immaterial facts (the time of day, the shopper's identity) are stripped out — removing them would not change the result.
- +1Legal issue. State the question of law the court had to answer: did the retailer owe, and breach, a duty of care in respect of goods it placed within a customer's reach?
- +1Ratio decidendi. Apply the shorthand material facts + legal issue = ratio: the binding rule is that a retailer who places goods within a customer's reach owes a duty to take reasonable care that those goods are safe to handle. That is the rule a later court must follow.
- +1Obiter dicta. The remark about a hypothetical injury in the car park under occupiers' liability was not necessary to decide this case (those facts did not arise), so it is obiter — persuasive only, never binding.
Key terms
- Stare decisis
- 'To stand by what has been decided.' The doctrine that a court follows the rulings of superior courts in the same hierarchy on sufficiently similar facts, giving the law certainty, consistency and equality.
- Ratio decidendi
- The binding legal rule for which a case is authority — the reason for the decision. Taught shorthand: material facts + legal issue = ratio. Distinct from the case's outcome, which is who won.
- Obiter dicta
- Statements 'said by the way' that were not necessary to the decision — for example, comments on facts that did not arise. Persuasive only, never binding, though senior-court obiter is often influential.
- Material fact
- A fact so central that, if it were removed or changed, the outcome would have been different. Identifying material facts is the first step in stating a ratio and in briefing any case.
- Binding precedent
- A ratio that a later court MUST follow because it comes from a superior court in the same hierarchy on sufficiently similar facts. Contrast persuasive precedent, which a court may follow but need not.
- Persuasive precedent
- A decision a court may follow but is not bound by — for example, a decision of a court in another jurisdiction, a lower court, or obiter dicta. Its weight depends on the strength of its reasoning.
Case Law & Precedent I FAQ
What is the difference between ratio decidendi and obiter dicta?
The ratio decidendi is the binding legal rule the case decides — the part later courts must follow. Obiter dicta are remarks not necessary to the decision (often about hypothetical facts), which are only persuasive. The practical test for obiter is whether the case would have come out the same way without the statement; if it would, the statement is obiter.
How do I actually find the ratio in a case?
Start with the material facts — the facts that, if changed, would change the result — then state the legal issue, and combine them: material facts + legal issue = ratio. The ratio is usually expressible in a single sentence. The difficulty is that judges state it at different levels of generality and sometimes there is no clear majority, so practise on short cases first.
Why does precedent bind at all?
Because stare decisis serves values the unit lists explicitly: coherence, justice, certainty, efficiency and equality before the law. Treating like cases alike lets people order their affairs and stops outcomes turning on which judge you draw. That is why identifying the binding rule accurately matters so much in assessment.
Can Sia help me practise finding the ratio?
Yes. Give Sia a short judgment or a case you are briefing and ask it to walk the material-facts-then-issue-then-ratio method with you and to separate ratio from obiter, one step at a time. It explains the reasoning and checks yours; it will not write your graded case note for you, and Monash academic-integrity rules apply.
Exam move
Precedent is a skill, so practise it, don't just read about it. For every case in the reading, write a one-sentence ratio using the material facts + legal issue formula, and separately note anything that is obiter and why. Keep a running list of the material-fact test applied to real cases so the 'would the outcome change?' question becomes instinctive. Because ratio-spotting feeds both the MCQ quiz and the case note in the 30% Research Assignment, it is the highest-leverage skill in the unit — over-invest here early. When a ratio is genuinely contestable (stated at different generalities, or no majority), write out both candidate ratios and argue which is narrower and better supported. Ask Sia to set you fresh short judgments and to check your ratio-versus-obiter split step by step.
Working through Case Law & Precedent I in LAW5000? Sia is AskSia’s AI Law tutor — ask any LAW5000 Case Law & Precedent I question and get a clear, step-by-step explanation grounded in how LAW5000 is taught and assessed. Read this chapter free, then take your hardest questions to Sia.
