The primary purpose of using a trademark is to distinguish or identify the source of a good or service that is used in commerce. Trademark law wants to avoid any consumer confusion with respect to the source of a product or service. A USPTO examining attorney will prohibit the registration of a trademark if the examining attorney determines that using a proposed trademark would likely cause confusion (likelihood of confusion) with an existing trademark. When the examining attorney reviews a trademark application, he/she must only consider the facts of the application that are in front of him/her and ignore any prior trademark ruling or decision.
Trademark law emphasizes that no one factor will determine whether consumers would likely confuse one trademark with another. All of the factors are looked at as a whole. In certain situations, some factors may be given more or less weight than others. The Trademark Trial and Appeal Board follows what are known as the “du Pont” factors when determining likelihood of confusion.