Author’s rights are protected by copyright law without recurring to any form of registration or formality, so that the work of an author is protected since the moment of creation. The purpose of this article is to analyse the cases in which a person register a sign as trade mark which is the property of another person and is protected by the copyright laws. In this analysis the focus is made on the practical issue, of how the author of the protected sign can take action so as to get trademark invalidation. Expressly provided by article 47 of the trademark Romanian Law no. 84/1998, trademark invalidation in the case of infringement of previous copyrights is left to the appreciation of the owner.