The purpose of registering distinctive trademarks is fundamentally to stop others from using such marks, which is to say to prevent others from using the same orsimilar trademark in Mexican territory. However, Mexican Trademark law provides for three instances in which trademarks may not be opposed, even if they areregistered. Such instances include the following: 1. – The trademark does not affect third parties who, in good faith, exploit the same or a similar trademark prior tothe date the registered trademark was applied for or prior to the date of first use declared by the trademark’s owner. This highlights the value that Mexican law grants to prior use of a trademark. 2. – Exclusive rights for exploitation of a trademark may not be claimed against those who use, commercialize or distribute under a trademark, if the trademark was legally introduced in Mexican territory by the holder of the registration or one who has been granted a license to use such trademark in Mexico. This is the case of parallel importations, in which legitimate trademarked products are imported and then commercialized or distributed by a third party that is not the owner of such trademark. Regulations on this point indicate the requirements that must be met in order for a product to be considered legitimate, which include: (a) introduction of the products into Mexico’s stream of commerce by a person who is the holder or licensee of a registered trademark; and (b) the holders of the mark registered in Mexico and abroad are, on the date that the importation occurs, the same person or members of the same economic group with common interest, or licensees or sub-licensees. 3. – Finally, one may not use a trademark against third parties, whether individuals or entities, if the trademarked words form part of such third party’s name or corporate name that is used to create or distribute products or services, so long as such use is in a customary form and has characteristics that may be distinguished from similar names.