In higher education and science, technology, engineering, and mathematics (STEM), interlocking oppressions can lead to inequitable environments for those who hold marginalized identities. Instructors can play key roles in either exacerbating or mitigating these inequities through their pedagogical approaches and choice of curricular material. However, it remains unclear how instructors who self-identify as committed to justice achieve higher levels of consciousness around areas of injustice and develop the self-efficacy to dismantle barriers for students over time. Here, we draw upon critical race theory and critical white studies to investigate what events or life experiences influence STEM instructors to understand the importance of social justice and examine how STEM instructors use this understanding to drive pedagogical shifts. We find variations in the ways that instructors' experiences and identities shape their understanding of justice. In addition, we uncover factors that influence the switch moment; curriculum and pedagogical shifts; their relationship to justice work broadly; and barriers and supports for justice work. These stories hold powerful lessons for STEM education, but also for education more broadly, both in terms of pedagogical practice and the questions that shape research agendas on equity in education.