So-called digital tracking and tracing systems have been proposed as a means to prevent the spread of SARS-CoV-2. There are ethical guidelines and evaluations of such systems available. As part of a research project, I will build on and critically evaluate the foundations of such guidelines. The goal is to provide both incremental improvements of the specific requirements for DTTSs and to present and discuss more fundamental challenge, the risk for indirect effects and slippery slopes. The nature of slippery slopes (...) makes ethical guidelines more difficult since it requires a more complex analysis than, for example, using a checklist allows for. (shrink)