There appears no logical place to indicate that some input is "required" for a group of checkboxes. If you inserted "required" into each checkbox, it would require that each checkbox be checked.

While checkboxes may be either checked or unchecked, a scenario is possible in which at least one checkbox would be required, such as asking the User which language she/he speaks. (Ostensibly this is at least one, as they are interacting with the form).

<select multiple> offers an alternative, but can be visually daunting; checkboxes provide an elegant method for the User to review his/her selections, at-a-glance.

Thank you for reviewing my bug submission.

John