IT systems design and architecture have many similarities with the design of organisations and institutions. Both pay attention to social concepts such as rules, norms, and values. Justice is one of the key concepts that can be relevant for any institutional design from a systems perspective. This paper outlines an ontology of justice based on the Unified Foundational Ontology (UFO). We envisage that it can support designers in recognising and addressing the issues of justice during systems design and analysis, including elicitation of requirements, rules analysis, systems evaluation, and policy analysis.