Design is increasingly recognized as an instrument of power. We explore power in the context of the Swedish welfare state and care institutions, which are undergoing political and structural reconfiguration as new technologies are introduced. Our aim is to better understand the effects of designed technologies within care institution and over care workers. Through our research, we have identified deviances, or gaps, between institutional policies and daily working practices, in which workers must cope within a grey zone of legality. Against this backdrop, we bring together and discuss concepts from philosopher Michel Foucault and sociologist Dorothy Smith in order to frame issues of power relevant to design. We elaborate upon these issues through a discussion of our project set in Swedish elder care institutions. Three 'research through (critical) design' examples illustrate ways and extents to which power is exerted over care workers. We discuss effects upon their subjectivity, including how their knowledge and agency can risk being ignored or overruled. Ultimately, we argue for design research to examine and articulate the (powerful) role of design in such contexts. We see this as a form of 'De-Scription' and active 'mapping' that can open up for wider debate and reconfigurations of power.