Legal Reasoning
Legal Reasoning tests method: extracting the rule from a passage or judgment, applying it to new facts, and avoiding inferences the text does not support.
Core tools
- IRAC: Issue, Rule, Application, Conclusion. The application step must connect each fact to an element of the rule.
- Ratio decidendi is the rule necessary to the decision; obiter dicta is persuasive only. A ratio may be narrowed later by distinguishing, overruling or disapproval.
- Precedent rules: per incuriam (ignoring a binding statute or decision), sub silentio (point not argued), stare decisis.
- Interpretation: literal rule; golden rule (avoid absurdity); mischief rule (Heydon's Case, 1584); purposive approach. Aids include definitions, provisos, explanations and maxims - expressio unius est exclusio alterius, ejusdem generis, noscitur a sociis, ut res magis valeat quam pereat.
- Reasoning forms: deductive syllogism, analogy (a fortiori, a contrario), inference to the best explanation. Presumptions include constitutionality and mens rea in penal statutes.
Worked example
A statute says an appeal must be filed within sixty days from the date of the order. A litigant files on day seventy. The literal reading bars the appeal; the court then asks whether the statute confers power to condone delay. Absent an express condonation provision, the limitation is mandatory and the appeal is dismissed as time-barred. Had the provision read may be filed within, the analysis would change.
Traps
- Treating every observation in a judgment as binding.
- Applying ejusdem generis where the list is exhaustive, not illustrative.
- Reading a proviso as an independent source of power.