Checking only the acceptance checkbox, the form will permit submitting, even if mandatory fields above are all empty.
I can provide a test case on a real site if you need (please email me for details).
Description of an example case:
I have a form with the following fields:
Current behaviour (wrong): If user checks only the acceptance checkbox, leaving blank the name, phone and date fields, and he/she hits the Submit button, the form will submit!
Expected behaviour (correct): the form must not submit until name, phone, date fields are filled!