The purpose of this chapter is to identify and analyse the basis and manifestations of constitutional good faith in the activities of the judiciary. The analysis proceeds from the presumption of good faith arising from the essence of the constitution as the supreme legal act. The main thrust of the analysis concerns the judicial application of the law, where good faith is manifested in the duty of loyalty and respect for the constitution, as well as honest conduct. Good faith is linked to the role of the courts in a democratic state and to the conception of the judicial office, the assumption of which is preceded by the taking of an oath. Judges have not only a legal but also a moral obligation to respect the constitution and apply its provisions in good faith. Due to the specificity and openness of the text of the constitution, its judicial application has certain distinctive features. Two of them are of fundamental importance. First, the interpretation of the constitution cannot be undertaken in isolation from the purpose of the regulation and its underlying axiological assumptions. Second, the established goals and objectives of constitutional provisions must be treated as a mandatory point of reference in the application of laws (i.e. pro-constitutional interpretation). This serves to realise the normative function of the constitution. Judges, being subject to the constitution, have the legitimacy to ensure that these values are respected and to guard the constitutionally defined limits of the operation of political power. The chapter concludes with an examination of judicial review and the implementation by courts of the role of “guardians” of the constitution.