In a contract, if there is a list where each item in the list is to be upheld, should the word “or” or “and” be used?

For example say there is a lease which aims to prohibit illegal activity in a house. What is the difference between stating:

1) “No illegal activity is permitted in the house, including manufacturing OR selling drugs”


2) “No illegal activity is permitted in the house, including manufacturing AND selling drugs”.

It would seem 2) is more correct as AND is showing the list is being added to, but could someone argue they were only selling drugs in the house, but not making them?

I know this is a bit of a silly example, but I red at the end of the day it’s really what someone can convince the jury of. What if someone really did interpret the contract that way (because they were dumb) then would that hold in court?

  • I can't answer this, but I once bought a car with a warranty that stated "30 days and/or 10,000 miles" -- due to a thrown rod 40 days/3,000mi after purchase and some dispute with the dealer I spoke with an attorney and was told it would take some legal research to find if there's a precedence to choosing "or" over "and" since "or" helped my case but "and" would harm my case. Since that point, I don't sign contracts with "and/or" in them at all. If it's not clearly spelled out, I refuse to sign.
    – Scott
    Jan 6, 2016 at 20:39

3 Answers 3


A court will look to the intent behind the words; a contract is not read as though it were written in Boolean logic. That is, they will try to determine from all the facts of the contract; which includes but is not limited to the written terms, what the parties agreed to.

In common usage, OR denotes exclusive alternatives and AND requires all elements to be present. For your example OR is better, however, it could be argued that if the person were doing both then they were not in breach - the court would doubtless treat that argument with the contempt it deserves. This is because the list is merely providing clarification of the essential term.

  • 1
    It's kind of easy when both "and' and "or" are referring to illegal activities. But what about situations like I posted in the comment above - where and/or isn't about criminal activity but about one interpretation benefiting one party and the other interpretation benefitting the opposing party?
    – Scott
    Jan 6, 2016 at 21:29
  • @SOIA Have to see the full context. Words and sentences are not interpreted in isolation. They are interpreted as part of a coherent whole.
    – user3851
    Jan 6, 2016 at 21:39
  • @Dawn and Dale M, my understanding is that for a contract to be valid, the party must understand and knowingly agree with the terms. What if a party really did interpret two conditions as "and" but the writer of the contract intended them to be "or". It wouldn't be unimaginable for the writer of a contract to try and be tricky and misleading, as is often the case. What I'm saying is sometimes it's not a matter of "common sense", so I guess in those situations its really up to the court to decide? Jan 6, 2016 at 23:54
  • If a contract is unambiguous, then it doesn't matter if one of the parties had some crazy understanding of what the words mean. If we drafted up a contract that said "clipclopshop will pay dawn 100 US Dollars if she mows clipclopshop's lawn", and I mow your lawn, you can't get out of it just because thought that "US Dollars" meant sand dollars found in the US.
    – user3851
    Jan 7, 2016 at 0:39

The Plain-Meaning Rule A principle used by courts that applies to both statutory and contract interpretation is the Plain-Meaning Rule. It provides that the objective definitions of contractual terms are controlling, irrespective of whether the the language comports with the actual intention of either party.

This rule provides a plausible legal basis for arguing that only a tenant engaged in both manufacturing and selling of drugs is in breach of the contract terms. While in your self-described "silly example", such an argument is unlikely to prevail, imprecise and/or ambiguous language in contracts can produce unexpected legal results.

  • The plain-meaning rule doesn't defer solely to "objective definitions"
    – user3851
    Mar 18, 2016 at 19:16
  • The plain meaning rule incorporates context and avoids reading terms in isolation from the rest of the statute, contract, etc.
    – user3851
    Mar 18, 2016 at 19:17
  • "So when deciding whether the language is plain, we must read the words in their context and with a view to their place in the overall statutory scheme." - King v Burwell.
    – user3851
    Mar 18, 2016 at 19:19
  • The "and/or" rule also says that "and" means "or" and vice versa, when it is convenient or necessary for interpretation. There are zillions of rules of construction, such as the last antecedent rule, and absolutely no ranking of the rules. Anyhow, in the face of actual linguistic ambiguity, justices are quite willing to assert that "the meaning of the text is plain".
    – user6726
    Mar 18, 2016 at 20:11
  • It entirely depends on whether "manufacturing and selling of drugs" is a single compound activity that is included as a prohibited illegal activity, or whether it is a list of two activities that are each included as prohibited illegal activities. As I see it, it's clearly the latter, but it's obviously possible to argue for the former. Another argument: even if "manufacturing and selling" is a single activity, that doesn't stop "manufacturing" and "selling" to be additional unnamed activities that are nonetheless illegal and therefore violate the lease, along with every other crime.
    – phoog
    Mar 18, 2016 at 21:43

There is no difference in what the two wordings say, because the "including" clause does not contribute anything to the situations identified as permitted. Manufacturing drugs is illegal, selling drugs is illegal, and therefore "No illegal activity is permitted in the house" all by itself prohibits either activity (and therefore both activities). The word "including" does not mean "specifically" – if the contract has said "specifically, manufacturing..." then there could be a question of whether other unspecified illegal activities are disallowed. It would not even be necessary to inquire into the intent of the tenant and the intent of the landlord in making this contract, and whether they didn't actually have a meeting of the minds.

That said, you should use "or", to reflect the fact that any one of these activities is supposed to not happen, and "or" means "any one". Interpretive problems arise when you have something negative to the left of a conjunction or disjunction, owing to De Morgan's Law ("not (A or B)" is different from "not A, or B").

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