In legal drafting, “and” versus “or” decides whether a list of conditions must all be met or whether any one of them is enough. “And” is conjunctive: every item applies. “Or” is disjunctive: any single item suffices. That single-word choice can move a case from liability to no liability, from a standard sentence to a mandatory minimum, or from a valid contract termination to a wrongful one. And courts don’t always read the words the way they appear on the page.
What “And” Does in a List
When “and” joins items in a contract, statute, or regulation, it stacks them. Compliance requires satisfying every one. Skip a single item and the whole requirement fails.
The pattern shows up across the law. A sentencing enhancement that applies when a defendant used a weapon and caused bodily injury forces the prosecution to prove both. Proof of one without the other leaves the enhancement out of reach. A loan covenant that requires the borrower to maintain insurance, submit quarterly financials, and keep the property in good repair treats each obligation as independently mandatory; missing any one is a default. The word binds the items into a single package, and the package is incomplete without every part.
What “Or” Does in a List
“Or” runs the opposite direction. It creates alternatives, and any one of them, standing alone, triggers the legal consequence. The Supreme Court has treated this as the default: terms connected by “or” are given separate, independent meanings, each carrying full weight on its own.1Legal Information Institute. Reiter v. Sonotone Corporation, 442 U.S. 330 (1979)
A termination clause allowing a company to end a vendor relationship if the vendor misses a delivery deadline or files for bankruptcy is satisfied by either event alone. Definitions work the same way: a statute defining “financial institution” as a bank, credit union, or savings association covers each entity on its own. The “or” tells you the list shows different routes to a single category, not stacked requirements.
When Courts Read “And” as “Or” (and the Reverse)
The literal rule bends when it produces an absurd result. The Supreme Court has acknowledged the problem openly, observing in DeSylva v. Ballentine that “the word ‘or’ is often used as a careless substitute for the word ‘and'” and that the trouble “has been with us for a long time.”2Justia. DeSylva v. Ballentine, 351 U.S. 570 (1956)
DeSylva itself made the swap. The Copyright Act used “or” to connect a list of people who had priority over executors in renewing a copyright. Read literally, the executors could step in as soon as any single person on the list died. The surrounding text made clear the executors should inherit only after all of those people were gone, so the Court read “or” as “and.”2Justia. DeSylva v. Ballentine, 351 U.S. 570 (1956)
Private contracts get the same treatment. In Weinberg v. Waystar, a partnership agreement gave the company a repurchase right triggered by a participant’s departure “and” a breach of a restrictive covenant. Read conjunctively, both events had to occur. The court concluded from context that the parties intended either event to trigger the right independently, and it read “and” as “or.”
The default still holds: “and” means all, “or” means any. Courts swap them reluctantly, and the party asking for the swap has to show that the literal reading is genuinely unreasonable. The flexibility is a safety valve, not a license to draft loosely.
Why “And/Or” Causes Problems
“And/or” tries to express three possibilities in a single term: A alone, B alone, or both together. That triple meaning is exactly what creates the ambiguity when a dispute reaches court. Judges and commentators have criticized the construction harshly, calling it a “Janus-faced verbal monstrosity” and an “inexcusable barbarism.”
A clause imposing a penalty when an employee violates a non-compete “and/or” a confidentiality agreement leaves the key question open. Must the employer prove both? Either? The answer depends on which reading a judge finds more persuasive, and reasonable readers can land on opposite sides.
The cure is to say what you mean. If any single violation triggers the penalty, use “or.” If both violations are required, use “and.” If you need to cover the both-or-either scenario explicitly, spell it out: “violates the non-compete agreement, the confidentiality agreement, or both.” Those extra words end the ambiguity.
How Modifiers Attach to Items in a List
Connectives also interact with qualifying phrases in ways that change which items a modifier reaches. Under the last antecedent rule, a limiting phrase ordinarily modifies only the word or phrase immediately before it, not the entire list.
The Supreme Court applied the rule in Lockhart v. United States. A sentencing enhancement listed prior state convictions for “aggravated sexual abuse, sexual abuse, or abusive sexual conduct involving a minor or ward.” The question was whether “involving a minor or ward” applied to all three offenses or only the last. The Court held it modified only “abusive sexual conduct,” the phrase it immediately followed.3Legal Information Institute. Lockhart v. United States, 577 U.S. 347 (2016)
The consequence was concrete: a prior conviction for sexual abuse of an adult qualified as a predicate offense and triggered a mandatory minimum that would not have applied if the modifier reached the whole list. The rule isn’t absolute. When a list has clear parallel structure and the modifier logically applies across the series, courts sometimes extend it. But the narrow reading is the default.
How Punctuation Changes the Scope of a List
The punctuation around a connective can shift a list’s meaning as much as the connective itself. In O’Connor v. Oakhurst Dairy, Maine’s overtime statute exempted workers involved in “the canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of” perishable foods. Without a serial comma before “or distribution,” delivery drivers argued the final item was the single compound activity “packing for shipment or distribution,” not two separate activities. Because they distributed but did not pack, they claimed the exemption did not cover them. The First Circuit agreed the language was ambiguous and ruled for the drivers. The case later settled for $5 million, and Maine’s legislature rewrote the statute using semicolons.
The “or” in that statute was supposed to separate two exempt activities. Without the serial comma, it looked like it described one. Five million dollars turned on a punctuation mark.
Drafting to Prevent Disputes
Most connective fights are preventable. The strongest technique is to signal conjunctive or disjunctive intent in a lead-in phrase before the list begins, so the reader knows the structure before reaching the individual items.
- For conjunctive lists, introduce with something like “The applicant must satisfy each of the following conditions,” then number the items. Even if “and” gets dropped from the final item, the lead-in controls.
- For disjunctive lists, introduce with “The contract may be terminated upon the occurrence of any of the following events.” The word “any” does the work regardless of how the items are punctuated.
A few other practices reduce risk. Use semicolons rather than commas to separate complex list items, especially when the items contain their own internal commas. Always include the serial comma before the final connective. Replace “and/or” with the specific combination you intend. When a qualifying phrase should apply to every item, repeat it after each one or move it into the lead-in clause; don’t attach it only to the last item and rely on a court to extend it backward.
Each of these habits addresses a dispute that has actually gone to litigation, sometimes to the Supreme Court. Restructuring a list at the drafting stage costs a fraction of what it costs to litigate what the list means.