Sumptuary laws (from Latin sūmptuāriae lēgēs) are laws that try to regulate consumption. Black's Law Dictionary defines them as "Laws made for the purpose of restraining luxury or extravagance, particularly against inordinate expenditures for apparel, food, furniture, etc." Historically, they were intended to regulate and reinforce social hierarchies and morals through restrictions on clothing, food, and luxury expenditures, often depending on a person's social rank.

Societies have used sumptuary laws for a variety of purposes. They were used to try to regulate the balance of trade by limiting the market for expensive imported goods. They made it easy to identify social rank and privilege, and as such could be used for social discrimination. They could also be used to prevent, or at least reduce opportunities for political bribery and corruption.

The laws often prevented commoners from imitating the appearance of aristocrats, and could be used to stigmatize disfavoured groups. In Late Medieval cities, sumptuary laws were instituted as a way for the nobility to limit the conspicuous consumption of the prosperous bourgeoisie. Bourgeois subjects appearing to be as wealthy as or wealthier than the ruling nobility could undermine the nobility's presentation of themselves as powerful, legitimate rulers. This could call into question their ability to control and defend their fief, thus inspire traitors and rebels. Such laws continued to be used for these purposes well into the 17th century.