Must, Shall, and Will Use ‘must’ instead of ‘shall.’
Must denotes obligation (You must attend!) or indicates a necessity to act (You must behave).
Shall imposes an obligation to act, but it may be confused with the prediction of a future action. Shall is commonly used today in questions requesting an opinion or a preference (Shall we go?), expressing determination (I shall return!), or in formal regulations that express a requirement (Applications shall provide a proof of certification).
Will predicts future action rather than a prediction. (Will we go?)
Should infers obligation, but not absolute necessity. (Should we go?)
May indicates discretion to act. (You may go.)
May not indicates a prohibition. (You may not eat that.)
Notes:To impose a legal obligation, use must.
In most contexts, will is preferred over shall.To predict future action, use will.
DON’T SAY: The Governor shall approve it.
SAY: The Governor must approve it. [obligation]
OR: The Governor will approve it. [future action]