Carnivore predation on livestock often leads people to retaliate. Persecution by humans has contributed strongly to global endangerment of carnivores. Preventing livestock losses would help to achieve three goals common to many human societies: preserve nature, protect animal welfare and safeguard human livelihoods. With public interest in carnivore conservation rising, many non-lethal interventions have been implemented. Between 2016-2018, four independent reviews synthesized 40 years of research on the effectiveness of lethal and non-lethal interventions for reducing predation on livestock. From 114 studies, the reviews arrived at strikingly similar conclusions: scarce quantitative comparisons of interventions and scarce comparisons against experimental controls preclude strong inference about the effectiveness of methods. If policy is meant to regulate the use of public resources invested in protecting livestock and carnivores, then evidence of effectiveness should be a prerequisite to, or at a minimum measured during, policy-making or large-scale funding or implementation of an unproven method.