Malpractice law is frequently justified by the claim that it improves health care services but this belief remains untested. Using a multiple case study in 16 remote rural areas in New Zealand, this study examined the effects of formal quasi-judicial investigations on the quality of health care services. The study found that the fragile local health systems were damaged by the quasi-judicial investigations of the medical disciplinary body and became less efficient and less user-friendly. A few doctors left rural practice and were difficult to replace. The remaining health workers responded to the investigations in a negative manner, losing confidence, enthusiasm and motivation for work; they performed in a less efficient manner, working more slowly, setting up barriers to access, ordering more tests and referring more to secondary care. Complainants also appeared to have been disadvantaged as a consequence of having complained.