Background <p>People who co-use opioids and methamphetamine have high rates of incarceration. The criminal legal system is therefore increasingly tasked with providing substance use disorder treatment, including medications for opioid use disorder (MOUD). Unfortunately, treatment in carceral settings remains inconsistent and little is known about how people who co-use experience these treatment pathways. This qualitative study addresses this gap by analyzing how people navigate these overlapping systems of punishment and care.</p> Methods <p>We conducted in-depth, semi-structured interviews with 20 hospitalized patients in Washington State initiating MOUD with recent methamphetamine use and past-year criminal legal involvement. Interviews explored substance use trajectories, legal system contact, and treatment experiences. Using thematic analysis grounded in ethnographic principles, we identified common strategies and challenges participants faced in accessing and engaging with treatment.</p> Results <p>Participants described legal system involvement as stigmatizing, unpredictable, and difficult to escape. Metaphors like “entrapment” and “contagious” were used to make sense of the legal system’s disruptive role and to show how social and structural factors increased people’s vulnerability to the legal system itself, sometimes in substance-dependent ways. To navigate this legal environment, participants adopted strategies of both compliance and non-compliance, toggling between them to minimize risk of harm and maintain autonomy. These same strategies were carried over into carceral treatment, which was often experienced as an extension of punishment and ill equipped to meaningfully capture polysubstance use.</p> Conclusions <p>This study contributes to the literature on carceral treatment, detailing the lived experience of people who co-use opioids and methamphetamine with treatment access and legal system involvement as the two become more tightly linked. Mandated treatment often replicates carceral control and fails to accommodate the realities of polysubstance use. People who co-use developed adaptive strategies to navigate these systems, reflecting the need for treatment models that respect autonomy and reduce harm rather than criminalize. Our findings thus support the need for policies that provide consistent access to care and disentangle treatment from coercive legal oversight.</p>