The present study is a first approach to legal translation from Portuguese into Spanish. Taking the Portuguese Constitution of 1976 (including the different revised versions) as our starting point, we analyze the false friends we have identified in five translations rendered by specialists in Constitutional Law. We find that most examples of interference are due to the linguistic proximity between Portuguese and Spanish and a lack of distance from the source text. We conclude that many false friends could have been avoided had the translations been revised by professional translators.