Shall, Will, Must, Should, & May

Do they have to?

What do they mean?

The differences between these words is pretty simple and straightforward. It is important to use the correct word, as precision of meaning matters.

~~shall~~: imposes an obligation to act, but may be confused with prediction of future action - can mean "must", "may", or "will"
will: predicts future action
must: imposes obligation, indicates a necessity to act
must not: indicates a prohibition
should: infers obligation, but not absolute necessity
may: indicates discretion to act

Must: The Replacement for Shall

Even though "shall" is the currently preferred word in the Model Constitution due to historical realities, legal language has moved away from its use and toward the more modern "must".

Note: See #3 on Drafting Legal Documents on Archives.gov for more details.

Note: For a more full discussion on "shall", see this FAA article.