(Latin: “let the buyer beware”), in the law of commercial transactions, principle that the buyer purchases at his own risk in the absence of an express warranty in the contract.

As a maxim of the early common law, the rule was well suited to buying and selling carried on in the open marketplace or among close neighbours. The increasing complexity of modern commerce has placed the buyer at a disadvantage. He is forced to rely more and more upon the skill, judgment, and honesty of the seller and manufacturer.

The modern law of commercial transactions recognizes this and protects the buyer by implying various exceptions to the principle of caveat emptor. Thus, in the case of a sale by sample, the law implies a condition in the contract that the bulk of the merchandise will correspond with the sample in quality and that the buyer will have a reasonable opportunity to examine the bulk of the merchandise. Likewise, when the buyer has made known to the seller the particular purpose for which the goods are required, the law implies a condition in the ensuing contract that the merchandise is of merchantable (average) quality and reasonably fit for the intended purpose.