Compounding histories of injecting drug use and incarceration can marginalise people engaging with services, making it difficult for them to address their health and social welfare needs, particularly when they navigate community re-entry service supports. Drawing on Hall and colleagues' five components of trust, this paper seeks to understand how trust in service providers fosters (or inhibits) effective service engagement from the perspective of people who inject drugs during the prison post-release period.

Between September 2018 and May 2020, qualitative in-depth interviews were completed with 48 adults (33 men, 15 women) recruited from SuperMIX (a longitudinal cohort study of people with a history of injection drug use in Victoria, Australia). Data relating to service engagement were coded against the five components of trust: competence, fidelity, honesty, global trust, and confidence.

Reflections of post-release service engagement frequently focused on interactions with community corrections (parole) officers. Depictions of trust were consistently portrayed within the context of negative experiences and deficits, whereby trusting provider relationships and interactions were rarely described. Most participants recounted a stark absence of fidelity (that is, "pursuing a [client's] best interests"), with some participants detailing circumstances in which their vulnerability was purposefully, almost strategically, exploited. These encounters nearly always had the consequence of impeding the participant's positive progression in the post-release integration period.

There is an urgent need to prioritise the client in health and social service delivery in the post-release transition-to-community period and recognise the importance of trust in delivering effective services to people whose life histories make them highly vulnerable to marginalisation.