Another Skirmish in the “Shall” Wars

Today a reader posted the following comment (found here):


I have been pushing your rules about shall and must since I started drafting contracts. Recently, a colleague said that we should use must exclusively. He pointed to the following link to bolster his case:…

I wanted to point it out for your opinion.


If you want to be heard in the marketplace of ideas, you have to point out the frailties in the other guy’s ideas. Repeatedly. So here goes:

That link is to an item on the website of the Federal Aviation Administration. The title is What’s the only word that means mandatory? Here’s what law and policy say about “shall, will, may and must.” It’s by one Bruce V. Corsino, the FAA’s “Plain Language Program Manager.”

Dr. Corsino is no schmo. You can find out more about him in this article in Harvard Magazine. It says that Dr. Corsino is a trained psychologist and medical ethicist and a retired colonel in the U.S. Army medical department. That tells us two things: First, he’s not a lawyer. Or to put it more specifically, he’s not a transactional lawyer. And second, he’s not a linguist.

Those two factors explain why, for purposes of contracts, Dr. Corsino’s advice is bad to the point of being obnoxious.

For one thing, someone apparently granted Dr. Corsino power over the English language. Here’s how his article opens:

We call “must” and “must not” words of obligation. “Must” is the only word that imposes a legal obligation on your readers to tell them something is mandatory. Also, “must not” are the only words you can use to say something is prohibited.

So must is the only word? Most transactional lawyers and commentators on legal writing would take issue with that. In contracts, drafters use many different verb structures to express obligations. Most of those verb structures are wordy or confusing, but nevertheless, there they are. At the more disciplined end of things, my book A Manual of Style has recommended, through three editions, that you use shall to express obligations imposed on a party that’s the subject of a sentence. The fourth edition, due in September, will do the same.

This supercilious tone pervades the article. Here’s some more:

Until recently, law schools taught attorneys that “shall” means “must.” That’s why many attorneys and executives think “shall” means “must.” It’s not their fault.

I’m not going to rehash arguments I’ve made elsewhere (for example, in this 2014 article), but here’s how I would rebut Dr. Corsino’s assertions as regards expressing obligations in contracts:

  • Other kinds of writing don’t use shall? That makes sense, but the prose of contracts is limited and stylized, and a lot is at stake, so different constraints apply. To get a sense of that, you could do worse than look at my draft “quick reference” guide, in this post, to what I call “the categories of contract language.” Contract drafters can safely ignore nostrums intended to apply to writing generally.
  • But FAA Plain Language Writing Order 1000.36 says you should use must even in contracts? Lawyers at the FAA might have to pay attention to that, but no one else has to. The marketplace of ideas is cacophonous, so you have to sort out the good ideas from the not-so-good.
  • I’ve debunked the notion that using shall is risky. That’s something I addressed most recently in this post, which is the one that prompted the reader comment I quote above.
  • The notion that must holds sway to express obligations would come as news even to Bryan Garner, whom Dr. Corsino cites. Garner favors will, not must, although his reasons don’t make sense, as I note in this 2011 post.

So I suggest that Dr. Corsino is out of his depth. For purposes of contracts, I recommend you ignore his advice. His article doesn’t reflect the reality that which verb structure you use isn’t a matter of right or wrong: instead, it’s a judgment call.

About the author

Ken Adams is the leading authority on how to say clearly whatever you want to say in a contract. He’s author of A Manual of Style for Contract Drafting, and he offers online and in-person training around the world. He’s also chief content officer of LegalSifter, Inc., a company that combines artificial intelligence and expertise to assist with review of contracts.

3 thoughts on “Another Skirmish in the “Shall” Wars”

  1. Dear Ken,

    A few comments:

    1/ I like the tone of the post. Civil, but without pulled punches.

    2/ Since contracts are essentially memoranda of obligations, nothing is more important than expressing obligations well, so the ‘shall’ battle is crucial. Fight on!

    3/ You have made the case overwhelmingly and for a long time that the disciplined use of ‘shall’ is the best way to express a party’s duty. Kudos! I think it’s your legacy, even more than the [rest of the] categories of contract language.

    4/ Defining ‘shall’* — I know you think it needless — might win unconverted drafters over to MSCD’s way of using ‘shall’. If so, isn’t the tiny price worth paying?

    *In this agreement, ‘[a party] shall’ means ‘[that party] takes on a duty to’.*


  2. Ken

    I think you’re being unduly critical. Dr. Corsino is on our/your team, and IMHO of all the sins, ‘must vs shall’ is in the absolute lesser category.

    Second, he does not purport to write only for contracts, so criticizing on that basis is at least slightly misleading.

    Further, your ‘limited and stylized’ argument is perfect backup for those looking to protect ‘represents and warrants’, ‘such parties of the first part’ and ‘said obligation’ on the same basis.

    The first contracts law partner I worked for described ‘shall and must’ as two churches of religion. The one thing they had in common was that the other was wrong.

    Keep up the good fight! (…you must).

    • I agree that if I’m debating shall versus must with someone, we probably agree on a lot of other issues. But the nature of the debate is relevant, too. Because Dr. Corsino is unaware of how ill-informed he is, he permits himself high-handed pronouncements. I have no confidence in him, period. I don’t want him on my team.

      That he doesn’t limit himself to contracts is irrelevant. His advice isn’t any less bad because he says it also applies to other kinds of writing.


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