This article discusses a judicial decision in Portugal highlighting a procedural error related to the principle of adversariality (contraditório) in civil proceedings. Specifically, it emphasizes that in incidents such as opposition to a garnishment, courts must allow parties to respond to all evidence and arguments before issuing a decision on the merits. The case reviewed involved a court ruling without giving the parties, particularly the defendant, the opportunity to contest witness testimony or respond to evidence, violating the constitutional principle of adversariality outlined in Article 3, nº3 of the Portuguese Civil Procedure Code. The decision was deemed a procedural nullity due to this breach, underscoring the importance of respecting procedural rights to ensure fair trial standards in Portuguese civil law.