Friday, April 25, 2008

Loose Canon: Expressio Unius

Starting Wednesday, I've got 4 exams in 9 days, so I'm excusing myself from my aspiration to 1-2 substantive posts a week for the next little while. Today, a short and poorly-edited post on the canon known as "Expressio Unius est Exclusio Alterius," which means "expression of one thing is the exclusion of others."

Justice Scalia's illustration of the canon in his book "A Matter of Interpretation" is roughly as follows. A sign that says, "No children under 12 admitted" can be interpreted to entail that people over 12 are admitted, or at least qualify for admission on the basis of age.

A sensible rule for cases in which it works, but in general this canon is sketchy beyond belief. It's an incredibly "loose" canon, in the sense that it can be used to justify almost anything. It is not surprising, therefore, that Justice Scalia, who is generally skeptical of canons of statutory construction, likes this one. It allows him to exercise his willfulness while pretending to be faithful to the text.

To illustrate, take this text, from a sign at the entrance to the Case Law Library's computer lab:
Using the canon of Expressio Unius, we can determine that one may remove the computers from the lab; or that one can remove chairs from the other computer lab.

Most judges, of course, would reason that the authority who put up the sign could not possibly have meant these things, and would not make this determination. But to textualists like Justice Scalia, or Chief Judge Frank Easterbrook of the Seventh Circuit, intent is not a relevant consideration, unless it can be disguised as something else.

Which brings me to another point about Expressio Unius - it involves reasoning about intent. To reach a conclusion that something that is not explicit in the text should be read into the text, one invokes Expressio Unius to reason that the person producing the text surely intended it to be in the text. It's an instance of the dog-not-barking type of reasoning that judges are rightly skeptical about, and it ought to be treated as such.

Why is Expressio Unius such a loose canon? My answer is focus structure, a topic I admit I know little about. Focus is used to highlight the part of an utterance which one wishes to contrast with unexpressed alternatives. For example, if I say "Do not remove CHAIRS from the lab," I'm implicitly authorizing the removal of items that contrast with chairs, but not implying anything about the removal of chairs from other labs.

The problem with laws and focus is that they're written down. In spoken English, the way to mark focus is stress and intonation, but these things are not recorded in written English.


The Ridger, FCD said...

As always, context is equally important. One can reason that everyone already knows not to take computers out of the lab, but the chairs might possibly be up for grabs.

More probably, someone has in fact taken chairs in the past and this sign is directed at them.

Uri said...

Oops - forgot to return to this comment until now.

Yes, context is important. It's important for syntax and sentence semantics and absolutely crucial for pragmatics and lexical semantics.

That's why doctrines of interpretation that minimize the importance of context often lead to results that are absurd or plainly unjust. The doctrine of expressio unius is an attempt to formulate a broad pragmatic principle, but as my example shows, it is much too broad, and requires the person applying it to use her knowledge of context and her common sense. For this reason, a doctrine like textualism can't be rescued by linguistic canons like expressio unius.

Anonymous said...

Potential misuse of a legal maxim doesn't diminish its value for use when appropriate. Please see:

Uri said...

I agree. Judges must use common sense when interpreting texts, and the pragmatic principles of linguistic communication that are overbroadly captured in the Expressio Unius principle are part of common sense interpretation based on the judge's knowledge of language and communication. A decent judge should use her judgment as to what inferences can be drawn from the inclusion or exclusion of particular strings of text.

I believe this goes against the spirit of the textualists, who seek to eliminate this kind of judicial discretion by rigidly applying canons such as Expressio Unius.

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