I am a German law student and I am writing a thesis about the Arbitration Act 1996. I was asking myself what is the difference between "null" "void" and "invalid". I already found some answers, like this What's the difference between "null" and "void" in legal language? I have already learned that there is a difference between to void and nullify something.

But I cannot find anything about "invalid" or "invalidity". Maybe it is more difficult for me because I am from another country. My main question is: Is "null and void" = "invalid"? Or are there reasons an agreement can be "invalid" but not "null and void"? Or do you use "void" for agreement and "invalid" for contract?

Thank you very much for your answers :)

  • Have you tried asking in law.stackexchange.com?
    – Evan
    Commented May 25, 2017 at 12:49
  • Thank you Evan and Yosef for the hints. I think your lay understanding could be right. I am just going to ask there to be safe.
    – hdddd
    Commented May 25, 2017 at 13:14
  • Lay understanding: A contract that is invalid was never valid when it originally written. For a valid contract, a judge can later deem it void due to actions of either party. For example, a contract to sell a diamond for $1 is directly shown as invalid when argued as a typo, whereas the agreement could be valid between friends. Commented May 25, 2017 at 13:19
  • "Legalese" is famous for consecutive synonyms (e.g., "any and all," "cease and desist," and of course "null and void." Simply adding the word "invalid" is the icing on the cake of legalese. A contract which is lacking in any one or more of the criteria for a valid contract would make the contract invalid; thus, null and void. Commented Oct 13, 2017 at 18:22

1 Answer 1


There is no difference between "null" and "void" and to understand why it helps to know a little about the history of the common law of England.

After the Norman Conquest, the law was written for the most part in French and Latin. By the 1500's the law was written in French and English. There was a fear that by using the French word only meaning which lay in the English word would be lost, or used as a loophole, thus both words were used. Null and void, to have and to hold, to cease and desist are all examples of this tendency towards parallel construction in legal writing. The words "valid" and "invalid" refer to a wholly different matter. You might have an invalid provision in an otherwise valid contract, such as a provision that the parties agree that mandatory overtime rules will not apply. Keep in mind also that there are voidable contracts, such as a contract entered into by a minor. Such a contract has valid clauses but can be voided by the minor at any time (this is somewhat of a generalization).

I don't know what @Yosef Baskin meant by, "for a valid contract, a judge can later deem it void due to actions of either party." A party's later actions may constitute a breach of contract, but a breached contract is not a void contract. A contract whose object is illegal, such as murder, is void, or null and void. An otherwise valid contract is not made void by the subsequent performance or non-performance of the parties. A change in the law may void a contract in whole or in part, such as a law prohibiting the sale of a particular commodity.

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