Mr. Mueller is engaged in the study of values in Roman law and in the decisions of the Federal Constitutional Court („Grammatik der Rechtfertigung“, the latter https://www.laws-of-social-cohesion.de/Projects/Modes-of-producing-law_-basic-values/index.html) as well as the development of software for building scietific data bases („DatabaseConstructor“, https://www.jura.fu-berlin.de/en/forschung/fuels/Projects/DBConstructor/index.html).