Commitments decisions have become one of the key mechanisms of antitrust intervention in the modernisation era. What was designed to be a marginal modification of the Commission’s enforcement toolbox has developed into the de facto default mechanism for applying EU antitrust in non-cartel cases and has spread out to national competition law systems. Notwithstanding the enthusiasm of enforcers and undertakings, several members of the antitrust community have highlighted actual or potential weaknesses of the said tool focusing on specific aspects of its design or on certain cases. These studies, despite their unquestionable value, discuss commitments in a fragmented way and/or without articulating a general conceptual framework for assessing them. This is the first work that studies commitments decisions in a systematic way and under a novel theoretical framework.  The aim of this thesis is twofold: (a) to identify commitments’ idiosyncrasies and limitations and discover ways to optimize their function, (b) to do so, on the basis of a broader theoretical framework capturing how antitrust institutions operate in the post-modernization era and how their functioning can be improved. The main argument is that commitments are a manifestation of a broader tendency in EU antitrust towards a Responsive Law model that seeks to ensure law’s integrity. Thus, they can be refined by adopting the key prescriptions of the Responsive Law modus operandi.  Specifically, this thesis is arguing that commitments set up multilevel conversations increasing enforcers’ learning input and allow them to use competition norms as multifaceted screens for assessing and guiding mixed behaviour. Thus, antitrust enforcers can use commitments to achieve precision strikes and combine them with other tools to deploy various enforcement strategies. In this sense, commitments are a Responsive Law tool and could make antitrust more responsive if fine-tuned.  Yet, commitments can undermine crucial Rule of Law values, such as procedural justice, legal clarity and certainty, and thwart EU antitrust as a purposive mission by chilling private enforcement, by leading to inefficient outcomes, or by triggering systemic risks. To put it briefly commitments can hurt antitrust integrity. To address this issue, it is proposed here that competition authorities could function as responsive enforcers and courts as responsiveness catalysts.