Anyone who violates the rules will be severely punished, no exceptions.
Tips
usage
贷 here means 'to pardon/to spare' (an old legal sense), so 不贷 = 'no pardon.' The phrase is a standard tagline in legal and disciplinary announcements — 一律严惩不贷 ('all will be punished, no exceptions').
register
Formal and authoritative. Common in news reports, court verdicts, and corporate disciplinary statements. Sounds too heavy for ordinary conversation.