draconian
Extremely harsh and unreasonably strict, especially about punishment.
Draconian describes a punishment or rule that seems excessively harsh or severe. When a teacher gives detention for being one minute late, or when a principal bans recess for the entire school because two students misbehaved, those responses might be called draconian.
You'll often hear draconian applied to rules that seem way out of proportion to the problem. A city law requiring jaywalkers to spend a week in jail would be draconian. A parent grounding their child for six months over a single forgotten chore would be imposing a draconian punishment.
The word suggests unreasonable strictness, where the penalty far exceeds what the situation calls for. Tough but fair consequences aren't draconian. Something deserves to be called draconian when mercy and common sense have been abandoned in favor of rigid, excessive severity.