At the risk of being called a "clever lawyer" (and I guess that's better than being a dumb one!) in this post I will explain what "canons of construction" are.
When the language of legal text (such as a constitution, statute, ordinance, regulation, contract, deed, or will) is ambiguous, lawyers and judges use interpretive tools called "canons of construction" to establish the meaning of the text. These canons have been used for centuries. For example, one familiar canon is that "criminal laws are to be strictly construed," that is, criminal laws are interpreted against the state and in favor of the defendant. This canon is called the "rule of lenity" and there are good reasons to support its use. First of all, people are presumed innocent until proven guilty in order to protect all of us against unjust punishment. Second, vague criminal laws violate our right to due process, because people shouldn't have to guess what the law is. Any vagueness in a criminal law is peeled away and discarded, and only if the law clearly applies to the conduct that the person engaged in may the person be convicted. For analogous reasons, any ambiguity in an insurance contract is interpreted in favor of the insured and against the insurance company. Insurance companies write these contracts and had better be ready to pay up if they have written a policy that could be construed either way.
Other canons of construction seem a bit more arbitrary. For example, there is a canon of construction that permits you to draw a negative implication from the language of legal text, and another one that authorizes you to assume that the rule in question applies in other similar situations. These two canons are in tension with each other; they give you opposite results. For example, suppose you are driving through the Nevada desert with your loyal kitty riding shotgun, it's 120 in the shade and there is no shade, and you pass by the "Last Chance Diner" which sounds ominous and you are hungry and thirsty so you pull in the parking lot where you are confronted with a sign that says "Dogs Allowed" decorated with the smiley face of a Chocolate Lab. Your cat, a Siamese, cannot read the sign, thankfully, and is unaware of the gross discrimination perpetrated by the owner of the restaurant. But then you think, "Perhaps the canon of ejusdem generis applies here!" (Many of the canons have cool Latin names.) "Surely the owner meant that other, similar housepets were also welcome!" (Being so thirsty, your thoughts all have exclamation points.)
But then your mental glass becomes half-empty as the depressing notion drips into your consciousness, "But if the expressio unius canon applies, the sign means that dogs, and only dogs, are invited onto the premises!" (The full name of this canon is expressio unius est exclusio alterius, meaning "To say the one is to exclude the other.")
Karl Llewellyn, a brilliant legal scholar who helped to write the Uniform Commercial Code, once compiled a list of 56 canons of construction. He arranged them in two columns, 28 on the left hand side of the page and 28 on the right, and he showed that for every canon of construction there is an equal and opposite canon of construction. He was making the point that we can't rely on the canons to solve a difficult question of construing the meaning of a law – we need to assemble more evidence of what the law is in order to know which canon of construction is more likely to be applicable in any particular situation.
The canons of construction come up in constitutional analysis all the time. Here is an example. The Second Amendment says, "A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed." Does this mean that people have the right to keep and bear arms only for military purposes, or do we also have the right to keep and bear arms for the purpose of personal self-defense? That was the main question that the Supreme Court had to answer in the Heller case earlier this year when it considered the constitutionality of the handgun ban in the District of Columbia. And while case could be characterized as boiled down to a choice between expressio unius versus ejusdem generis, the Court had to consider a lot of other evidence of what the law was – other language in the Constitution about the militia, debates in Congress over the wording of the Second Amendment, the wording of contemporaneous state constitutions, as well as the decisions and opinions from state and federal courts. It would not have been appropriate for the Court to simply pick a canon of construction and apply it without explaining why that particular canon and not its opposite applied.
The bottom line is that while the canons of construction are useful guideposts for constitutional interpretation when used in conjunction with other information, by themselves they are nearly useless. We need to look at other evidence of what the law is – both textual arguments and other types of legal arguments – to know which canon is more appropriate in any particular case. The next posting will describe intratextual arguments.
Wilson Huhn is a Professor of Constitutional Law at The University of Akron School of Law and is the author of the book The Five Types of Legal Argument. This is the third in a series of essays explaining how people can legitimately disagree about the meaning of the Constitution.
