In this paper we develop a framework for understanding how justice-related claims play a role in the dynamics of controversy in energy projects. We do so by distinguishing two interacting trajectories of assessment: a formal trajectory that is embedded in the legal system and an informal trajectory that is mainly embedded in public discourse. The emergence of an informal assessment trajectory can be seen as a response to a (perceived) lack of attention to particular concerns or values in the formal trajectory, i.e. 'overflowing'. The emerging informal assessment may subsequently lead to adaptations in the formal trajectory, which we refer to as `backflowing'. Based on insights from case studies on Dutch energy projects and literature on energy justice we identify three justice-related attributes that facilitate understanding of the emergence of controversies. These attributes are based on differences between the two trajectories in terms of 1) the way in which values are expressed, 2) the dimension of energy justice that is taken as a starting point, and 3) the democratic legitimization of assessment trajectories. In order to allow for legitimate and effective energy policy, overflowing and backflowing need to be addressed as interrelated rather than as separate processes.