Proportionality analysis (PA) is ever more widely used by national and international courts to balance public goals and/or private rights. Proportionality itself is a frame within which we often think as lawyers. Hitherto, it mostly seen as a rational process of decision-making. But is it? How far does the frame of the PA itself frame the decision-making of (judicial) actors? Do biases and heuristics influence the decision qua the way PA is set up; qua its decision-architecture? The paper aims to shed light on certain features of PA which might, depending how the analysis is conducted, influence the outcome of the decision due to biases and heuristics of the relevant decision-makers. We plan to test several biases and heuristics using experimental methods with German Administrative Judges later in 2020 and will present the Vignettes. This helps to understand the psychology of different decision architectures in order to better understand outcomes.