Assessing landfills in terms of sustainable development (SD) is a difficult task. Landfills might, for example, remain reactive for hundreds or even thousands of years, a fact that conflicts with the fundamental SD principle of inter-generative equity. The Sustainability Potential Analysis (SPA) is a comprehensive assessment approach that aims at assessing the potential of a system to hinder or support SD from a systemic perspective. In this paper, we present an initial operationalization of this approach for a pragmatic legal landfill assessment and its application to assess two prototypic Swiss landfills as part of a pilot study. Thereby, the six generic criteria of SPA are specified using 18 Functional Key Variables (FKVs), such as "control of pollutant release" or "resilience to intended human impacts." The first results from the pilot study indicate that SPA and its generic criteria provide a purposeful guiding framework for achieving a systemic and comprehensive SD assessment that seems (i) to be feasible for practical application, (ii) sensitive for relevant SD issues, and (iii) transparent for the addressees of the assessment results.