4.154 prohibition: 'shall not'

'Shall not' is used to say formally that a particular thing is not allowed. 'Shall not' is often used in written rules, laws, and agreements.

• Persons under 18 shall not be employed in nightwork.
• Equality of rights under the law shall not be denied or abridged by the United States or by any State.

'Shan't' is used in a similar way to 'will not' and 'won't'.

• You shan't leave without my permission.