We are seeing increasing work in bioethics to defend and define healthcare’s environmental responsibilities. Distinctions have been made between absolute healthcare exceptionalism, moderate healthcare exceptionalism, and non-exceptionalism. Yet, the philosophical grounds for healthcare’s duty to minimise its environmental impacts are often not well explained or clearly articulated in the bioethics literature. I first establish that different axes of justice—social justice, environmental justice (including climate justice), ecological justice—can each be used to ground a general duty for healthcare to minimise its environmental impacts. I show that those grounds, including the specific conceptions of justice they encompass, span a variety of underlying ontologies. I then demonstrate that the selected axis of justice and underlying ontology affects the nature—limits and content—of the resultant duty and, thus, whether the duty is understood in a way consistent with moderate exceptionalism, non-exceptionalism, or neither. Here, limits refer to what means are impermissible to utilise to uphold the duty, and content refers to what is required to uphold the duty. Ultimately, numerous different ways to understand the duty’s limits and content are shown to exist. To conclude, I consider whether reasons exist for favouring certain understandings of the duty over others.