We analyse policymakers’ incentives to fight corruption under different institutional qualities. We find that ‘public officials’, even when non-corrupt, significantly distort anti-corruption institutions by choosing a lower detection probability when this probability applies to their own actions (legal equality), compared to a setting where it does not (legal inequality). More surprising perhaps is the finding that policy-makers do not choose a zero level of detection on average, even when it applies to them too. Finally, corruption is significantly lower when the detection probability is exogenously set, suggesting that the institutional power to choose detection can itself be corruptive.