Although the CJEU’s interpretation of the content and meaning of the EU’s principle of effectiveness still sparks debates in legal doctrine, it is already clear that the case law on this principle is too far gone to turn it back. This chapter does not intend to deny or criticize the CJEU’s case law regarding this principle; instead, it assesses its impact on the practice of national courts. Due to the principle of procedural autonomy, EU law does not harmonize the rules of implementation in the consumer protection area. However, as demonstrated in this chapter, the content of the principle of effectiveness, as interpreted in the CJEU’s case law, provides consumers with additional remedies, and influences both procedural and substantive legal norms. Assessment of the effectiveness of national rules is carried out not in abstracto, but in concreto, case by case, which makes it fragmented and haphazard. This undoubtedly impedes national courts’ ability to apply EU law norms effectively and ensure that the execution of consumer rights is timely and effective.