SignificanceEmerging evidence shows that the boundaries of protected areas (PAs) and their level of protection regularly change, yet little is known regarding the underlying causes of these legal changes and their impacts on ecosystems. For PA degazettements (i.e., protection removals) in the state of Rondônia in the Brazilian Amazon we show that the PAs less effective in stemming deforestation are more likely to be degazetted. For those already deforested PAs degazettement had limited, if any, additional impact on deforestation. Consistent with the scientific literature recognizing that governance shapes conservation outcomes, governance that improves PA outcomes also improves their legal durability. Our evidence on such relationships suggests directions for research and the need for policymakers to reexamine conventional wisdom regarding PAs.