Truth-in-advertising

Overview
Under the Federal Trade Commission Act, truth-in-advertising requires that the:


 * Advertising must be truthful and non-deceptive;
 * Advertisers must have evidence to back up their claims; and
 * Advertisements cannot be unfair.

Additional laws apply to ads for specialized products like consumer leases, credit, 900 telephone numbers, and products sold through mail order or telephone sales.

And every state has consumer protection laws that govern ads running in that state.

Source

 * FTC, Advertising FAQ's: A Guide for Small Business (full-text).