The FTC Act prohibits unfair or deceptive advertising in any medium. The advertisement must tell the truth and not mislead consumers. A claim can be misleading if it leaves out relevant information or if it implies something that is not true. In addition, claims must be substantiated, especially when they concern health, safety, or performance. The type of evidence may depend on the product, the claims, and what experts believe necessary.
Sellers are responsible for claims they make about their products and services.
Third parties, such as advertising agencies or web site designers and catalog marketers, may also be liable for making or spreading deceptive representations if they participate in the preparation or distribution of the advertising, or know about the deceptive claims. Advertising agencies or web site designers are responsible for reviewing the information used to substantiate ad claims. They can not simply rely on an advertiser's assurance that the claims are substantiated. In determining whether an advertising agency should be held liable, the FTC looks at the extent of the agency's participation in the preparation of the challenged advertisement and whether the agency knew or should have known that the ad included false or deceptive claims. Catalog marketers should ask for material to back up the claims rather than repeat what the manufacturer says about the product.