“Or” Is More Complicated Than You Think: De Morgan’s Theorem in Legal Interpretation.
Disputes centering on how to interpret legal documents are common. Interpretation disputes take multiple forms, with some turning on things like legislative intent, a defined term used in a provision, or harmonizing seemingly conflicting provisions. Other times, interpretation disputes boil down to the meaning of a single word, like “or.”
At first glance, “or” may not seem ambiguous whatsoever. But depending on the context in which “or” is used, “or” can mean different things.
Consider the following examples:
- You may contact me by phone or email.
- You win or you lose.
While “or” is used in both examples, “or” means different things. In the first example, contact by phone is acceptable, as is email. Either or both are permissible. In the second example, “or” is used to mean you can either win or you can lose, but you cannot do both.
Interpretation can be more complicated when “or” is used in a context where a prohibition word is followed by things separated by “or,” as in the following easily understood examples:
- No smoking or vaping.
- No food or drink in the courtroom.
The above examples are commonly understood to prohibit both smoking and vaping, and both food and drink in the courtroom. Why? A basic principle of logic known as De Morgan’s Theorem teaches that the negation of disjunction is the conjunction of negations. Stated simply, “not (A or B)” means “not A and not B, which means the same thing as “not A nor B.” Therefore, “no smoking or vaping” is properly interpreted to mean “no smoking and no vaping.” Similarly, “no food or drink in the courtroom” is properly interpreted to mean “no food and no drink in the courtroom.”
In legal disputes regarding interpretation of “or,” applying De Morgan’s Theorem can determine the outcome. For example, in a case where a court had to decide how to properly interpret a statute that read, “no municipality shall be incorporated which contains less than one hundred legal residents or less than thirty voters,” the court concluded that a proposed municipality with more than 30 registered voters but less than 100 legal residents could not be incorporated. State v. Buffalo Chip, 951 N.W.2d 387 (S.D. 2020).
While careful drafting can help prevent interpretation disputes, documents like restrictive covenants and other contracts often use “or” in a manner that gives rise to interpretation disputes. Depending on the context in which “or” is used, a party’s preferred interpretation may not represent a proper interpretation. Consulting with an attorney before taking a position on how “or” should be interpreted is therefore often a wise choice.
The lawyers at Beresford Booth have great experience counseling clients on both drafting legal documents in a way that eliminates interpretation issues, and counseling clients on how to properly interpret legal documents. Please do not hesitate to contact us at info@beresfordlaw.com or by phone at (425) 776-4100 to see how we can help.