It is disconcerting how difficult some central ideas in law can be when they are used in practice. In theory, ascertaining the legal proposition decided in an authoritative case should be simple enough. It is called the ratio decidendi, and law students encounter the concept from almost day one.
An associated central idea in law also has a Latin name: stare decisis. This is the idea that decisions about what the law is should be respected and applied to the extent that they are relevant in subsequent cases. The law needs to be predictable in its application, not arbitrary. This is a requirement of what is often called the rule of law. Our society is orderly to the extent that we accept the rule of law.
When a case gets to the final appeal court, it must be open to contrasting results. Otherwise, it wouldn’t have got that far. If the ratio of the final court’s decision is easy to identify, it will be difficult for subsequent courts dealing with the same issue to apply the earlier decision differently. But controversy over the ratio makes the law uncertain and open to change.
Ramos v Louisiana, discussed here on April 25, 2020, is a good example of a case where the ratio of an earlier decision was open to different interpretations. That case is particularly interesting for Kavanaugh J’s discussion of when a precedent may be overturned.
Overturning a precedent is clearly a serious step to take, because it challenges the rule of law. It is far more preferable for the earlier ratio to be reinterpreted, with reasons explaining how it came to be misunderstood. In June Medical Services LLC v Russo USSC No 18-1323 (June 29, 2020) Roberts CJ, the swing vote, stressed the importance of following precedent.
One source of difficulty in ascertaining the ratio of multi-judgment cases is where concurring judges give reasons for taking a slightly different view of the law from the view taken in a joint judgment, and the joint judgment does not address those alternative reasons. This happened in Nguyen v The Queen [2020] HCA 23 (30 June 2020). Here, the judgments of Nettle J, and in particular of Edelman J, appear entirely persuasive, but the joint judgment, with which the concurring judges in other respects agreed, does not explain why those concurrences are faulty. It’s almost as if the Court was deliberately setting up an interesting exercise for law students.
