The thesis covers issues of constitutional design, legislative procedures and agenda control in presidential systems, with specific empirical application to four Central American cases in a comparative perspective. The results relate to the critical view that presidential systems are inherently prone to institutional deadlock, deriving from their rigid constitutional design. My findings suggest that constitutional rules only determine broad parameters of variation, and that greater attention should be paid to the endogenous procedural design of the legislative process of policy approval in the explanation of institutional performance and inter-branch dynamics. The work is comparative and bridges quantitative and qualitative analysis. The data employed are original and allow for an innovative connection between theory-driven hypotheses on the incentives for majority political actors to circumvent ordinary procedures and play strategically employing procedural choices and political outcomes, by assessing the patterns of legislative production. The hypotheses are generated with attention to the degree of aggregation of interests in the decision-making process, as a measure of the representativeness of the decision-making process and hence as a general characteristic of the everyday democratic process. In fact, while democracy is understood as a process and not as a formal procedure, it is important to observe procedures as subtle devices where majority actors may find embedded comparative advantages to impose their political agenda unilaterally. The analysis further represents a thorough effort of theory testing whereby a competitive assessment of informational theories of legislative politics, exogenous factors such as electoral pressures or endogenous contextual characteristics such as the degree of fragmentation and polarization on the floor, is unpacked and delivers important analytical refinements to these theories. Finally, the normative agenda for analysis includes a view on constitutional choice and on methodological biases in the literature of Comparative Politics which have a large impact on the research output. The theoretical, substantive and methodological implications of the findings are thus reinserted into a normative view on procedural justice and the quality of democracy.