Must vs. May / Shall vs. Should

Have you ever paid attention to the terms “must, may, shall, or should” when reading through transport regulations? Maybe…Maybe not. Well, if you weren’t already aware, these particular terms are significantly important to shipping dangerous goods. Listed below are the definitions of these terms per each Regulation and what they actually “mean” in my opinion.

International Maritime Dangerous Goods (IMDG) Regulations

Referenced in Foreword section

Shall = Mandatory (You better do it or it’s not going on the ship)
Should = Recommendatory (We strongly suggest you do, it’ll make us happy, but we can’t reject your shipment)
May = Optional (You do it if it makes you happy because it doesn’t matter to us)

International Air Transport Association (IATA) Regulations

Referenced in Section 1.3.1.3

Shall = Mandatory (You better do it or it’s not going on the plane, AND we will return it back to you with a big fat rejected stamp)
Must = Mandatory (Like I explained for “Shall”…it’s not going on the plane)
Should = Preferred requirement but not binding (We strongly suggest you “should” do it, it’ll make us happy, but we can’t reject your shipment)
May = Preferred requirement but not binding (So you “may” want to do it our way, but we will accept your shipment if you chose not to do it)

Transportation of Dangerous Goods (TDG) Regulations

Reference in Part 1.3 (2)(a)

Must = Imperative (No ifs and no buts, it’s done our way)
May = Permissive (We are giving you the freedom of choice)

49 CFR

Referenced in Part 171.9 (b)

Shall = Imperative (You don’t have a choice)
Must = Imperative (You can complain if it makes you feel better, but you still have to do it if you want to ship it)
Should = Recommendatory (We strongly suggest you “should” do it, it’ll make us happy, but we understand if you prefer not to)
May = Permissive (Freedom of choice)

Hopefully, my explanations are better than how the Regulations define these terms. Should you need help with these terms or any other interpretations in the Regulations, the Regulatory Experts at ICC Compliance Center are always here to help. Contact ICC at 1-888-977-4834 (Canada) or 1-888-442-9628 (U.S.), and ask for one of our Regulatory Experts.

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