A broad spectrum analysis of the Italian antitrust cases regarding anti-competitive agreements and abuse of dominant position has shown a significant tendency of the First instance Administrative Court to recalculate (in 52% of cases) the fines imposed by the Italian Competition Authority (AGCM). This conclusion seems confirmed, in a comparative perspective, by the low appeal rate (10%) to the Court of Justice of the European Union in the same matters. The data we have gathered raise some issues. Does the first instance court, in its judicial scrutiny, apply the same methodology adopted by the AGCM? Does the reassessment jeopardize sanction deterrence? This paper investigates the methodology implemented by the administrative judge in redetermining the monetary fines. The analysis of the AGCM proceedings builds upon a dataset of n. 524 fines imposed by the AGCM for abuse of dominant positions and anti-competitive agreements across the period 2000-2015. We examined, exclusively, the AGCM proceedings (n. 119) followed by an appeal ending up in a fine modification. The outcomes of the analysis show that the judicial review could in some case hamper the effectiveness of the fine. This risk may stem from a methodological uncertainty, which becomes greater as the Court strays from the guidelines the AGCM guidelines.