What is the implication of using shall versus will in writing a specification document?

For instance, lets say I have the paragraph, "upon by all parties involved."

All information between persons involved in this project will be kept confidential and limited distribution of information only to persons agreed upon by all parties involved.

Have I just exposed myself legally to allow a breach of confidentiality because I didn't use shall? What would use of shall/will in this paragraph imply?

Related, but does not fill my need: When should I use "shall" versus "will"?.

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    Historically, shall referred to obligation while will referred to personal volition. Few speakers still make the distinction, but in legal terms it is usually upheld. 'He will do it' thus means that he wants to do it, whereas 'he shall do it' means that he is obliged to do it. – Anonym Jan 31 '14 at 17:52
  • In what jurisdictions? This may differ from nation to nation, province to province and state to state. Even when the statutes are worded alike, it's possible for common law baggage from court precedents to change the meaning, possibly making this difficult to answer for certain. Sometimes contracts are even governed by a jurisdiction that neither party formally belongs to just because the terms are clearer.... – Tonepoet Jul 26 '15 at 22:59
  • @Anonym - Actually, will refers to a personal promise, not necessarily desire. One may very well promise to do something to which they have an aversion or even extreme unwillingness to do. – MrWonderful Feb 2 '16 at 21:57
  • I shall do ABC if you will do XYZ (vice-versa may also be used as needed). Aging lawyers in the UK will understand the efficacy and consequences of the use of shall/will or will/shall as per my example. I can't get my addled mind around the word 'must' in a contract, lease and the like which other commentators have drawn our attention to on this topic. – Peter Point Dec 2 '16 at 10:47

RFC 2119 is the standard here. If something must happen, you need to use Shall. So although not necessary legally, but logically you have exposed yourself to a breach.

I am not a lawyer. This is not legal advice

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    This has helped me by letting me figure out I can resolve my issue using less ambiguous terms such as "MUST" or "ARE REQUIRED" – Incognito Sep 23 '10 at 19:55
  • Could you not also use To Obligate. "You are obligated to..." – Arthor Oct 17 '13 at 16:09
  • According to RFC 2119, the terms should only be understood as necessarily being interpreted according to RFC 2119, if near the beginning of the document there is a piece of text stating that they should be interpreted according to RFC 2119 (or BCP 14 if you want to automatically absorb any updates). Some uses have stated that they are to be interpreted that way only if bold, capitalised, etc. – Jon Hanna Jan 31 '14 at 11:17
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    This answer was correct when written, but it is no longer correct. Shall no longer means must and no longer creates a mandatory obligation. – Ben I. Apr 13 '18 at 21:48

This is a late reply, but I happen to be looking into the difference between shall, will and must right now. What I find is the following, according to plain English:

  1. Will in a contract should reflect only the future tense (not create obligations to perform).
  2. Shall does not refer to the future. It can be paraphrased as "has the duty to" and refers only to capable subjects (meaning, Lessor, or Buyer shall do something, but not Property or Product shall).
  3. Must refers to the duty to perform of inanimate subjects (like the product or the property).

However, shall being the "most misued word in legal English", it is suggested to avoid using it altogether and to replace it with must, which is now being used for obligations of animate subjects as well.

This was useful: http://www.plainlanguage.gov/howto/wordsuggestions/shallmust.cfm and it quotes Bryan Garner so it's a good source.


Both "will" and "shall" are ambiguous, because they can denote prediction rather than obligation. Most legal writing experts now prefer the unambiguous "must", and I usually used that when I was a solicitor.

Here, for example, are the opening words from s.2 of the UK's Human Rights Act 1998: "A court or tribunal determining a question which has arisen in connection with a Convention right must take into account ..."

But someone signing a contract in which they said "I will do X" would be hard put to persuade a judge that they hadn't contracted to do X. The Law Society's "Standard Conditions of Sale" have been using "X is to do Y" since 1990.


Things are coming to an end.

See: https://www.faa.gov/about/initiatives/plain_language/articles/mandatory/

“Nearly every jurisdiction has held that the word "shall" is confusing because it can also mean "may, will or must." Legal reference books like the Federal Rules of Civil Procedure no longer use the word "shall." Even the Supreme Court ruled that when the word "shall" appears in statutes, it means "may."”


Late reply, but this page from FAA.gov looks very authoritative to me:

What's the only word that means mandatory? Here's what law and policy say about "shall, will, may and must." (https://www.faa.gov/about/initiatives/plain_language/articles/mandatory/)

The simple conclusion:

We call "must" and "must not" words of obligation.

  • Surely some mistake? The word "may" connotes the very opposite of the meaning of "mandatory". I may give you $100. In this example I don't have to do so but if I had said, "I shall give you $100", I would be obligated to a promise (though legally unenforceable) to hand over the money. – Peter Point Dec 8 '16 at 3:00
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    Hi Peter I had actually thought exactly the same way, but the page from FAA.gov gave me a different answer. I have changed my wording in recent documents accordingly. – golddc May 4 '17 at 3:12

Forgive my late input, however - at least in Britain - the court would unlikely look too closely at the words used, instead more emphasis will be placed on the underlying "thrust" of the statement.

Both words you identify imply the same thing, that something will be done. there is little need to worry further about the semantics. It would be much more prudent to re-word the entire "term" so that the provision is expressly conveyed:

Any information relating to this project will remain confidential and will not be released to third parties without prior agreement.

or a variation thereof.

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    Interesting, but as I'm not a lawyer, I'm sticking with MUST and ARE REQUIRED, which also adds to the trust. – Incognito Nov 9 '10 at 14:21

"shall" implies a sense of obligation and is therefore preferred in legal writing, while "will" does not

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    Where's your evidence? You don't think "You will do this" has a sense of obligation? – curiousdannii Sep 15 '15 at 13:24
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    Welcome to EL&U. As StackExchange prefers definitive answers, I encourage you to edit your submission to provide an explanation, examples, and references as may be appropriate. Without support, you have merely provided personal opinion from an anonymous Internet user. Please take the site tour and review the help center for additional guidance. – choster Sep 15 '15 at 15:30

In the first person 'will' denotes volition and 'shall' a consequence. 'I will go out' means I choose to go out. 'If it rains, I shall get wet' means the getting wet will happen though not of my choosing.

Confusingly, these meanings reverse in the second and third person. 'You shall go out' means I want you to go out. 'If it rains, you will get wet' is a consequence, not something I desire.

Shall is therefore appropriate for the creation of obligations because documents are written in the third person and the voice is the parties expressing their agreement, therefore stating what they wish and agree each party to do.

I would not worry about your document though because it would be hard to imagine a court not giving effect to the obvious intention of the clause.

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    Hi Andrwe, welcome to EL&U. Other answers suggest that this perspective, while once true, is no longer the case at law or in general use (the exception in some regions being for questions). Can you edit your answer to cite some recently published evidence to support your view? For further guidance, see How to Answer and take the EL&U Tour :-) – Chappo Jan 16 at 22:10

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