When a precedent is binding, not every sentence in it binds. Judges write a great deal: background, history, asides, predictions. Only part of an opinion is the rule later courts must follow.
Key idea
The holding is the rule of law necessary to decide the case on its facts. Dicta (singular: dictum; from obiter dictum, "something said in passing") are statements that were not necessary to the decision. Holdings bind later courts; dicta can only persuade.
Why it works
Why should only the holding bind? A court decides the dispute in front of it, after hearing both sides argue the questions that matter to that dispute. Remarks about other situations were not tested by argument and were not needed for the result, so treating them as law would let a court decide cases that were never before it. A classic way to tell the difference is Wambaugh's inversion test: reverse the statement and ask whether the outcome would change. If removing or reversing a proposition would not change the result, it is probably dictum.
Worked example: Find the holding
In the Rivera case, which statement is the holding, and which is dictum: (1) a marina owes paying customers a duty of reasonable care on its docks; (2) the same result would likely follow for a night-time trespasser?
- Rivera was a paying customer. Statement (1) decides her case: without it, the court could not reverse.
- Statement (2) is about a trespasser, a person not before the court. Reverse it ("a trespasser would lose") and Rivera still wins.
- So (2) was not necessary to the result.
Answer: (1) is the holding; (2) is dictum.
Worked example: A famous footnote
In United States v. Carolene Products Co. (1938) the Court upheld a federal ban on "filled milk" under a deferential test. Footnote four suggested that courts might look harder at laws aimed at "discrete and insular minorities." Holding or dictum?
- The case was decided under the deferential test: the ban was upheld.
- The footnote speculated about other kinds of laws not before the Court, so it was not needed to decide the case.
- It was dictum. Yet it became one of the most influential passages in constitutional law, shaping later doctrine.
Answer: Dictum, though later courts built on it.
The line is not always sharp. Later courts often decide how broadly to read a holding: as a narrow rule tied to the precise facts, or a wider principle. Lawyers on each side will argue for the reading that helps their client. And lower courts usually give great weight to considered dicta from the Supreme Court, even though they are not strictly bound.
Common mistake
Treating every sentence in an opinion as law. Ask: if this statement were removed or reversed, would the result change? If not, it is probably dictum. Check the facts too: a statement about parties or situations not before the court (other plaintiffs, other statutes, "even if…") is a warning sign.
This is an educational course, not legal advice.