Baumgärtel’s research concerns the human rights of vulnerable migrants such as refugees, asylum seekers and undocumented migrants. As a senior researcher of the NWO research project “Cities of Refuge” (2017-2022), he focused on the international legal obligations and policy initiatives of cities and local governments in the reception and integration of refugees. He also has a broader interest in issues of social justice and their connection to human rights, both as legal guarantees and as normative aspirations. At present, he is a Petar Beron Research Fellow (2024-2025) at South-West University in Blagoevgrad, Bulgaria, where he is conducting a project on the application of theories of exclusion in the context of migrants' rights. The project is financed by the Bulgarian National Science Fund.