The paper deals with the issue of the quality control over experts’ activities, the results of which are used for public administration purposes. The case in focus is the state control over temporary disability examination in the Russian Federation. This patient’s health evaluation provides the cause for sick leaves and ensures the functioning of the mandatory social insurance system. The study aims to reconstruct routine procedures and practices of external control over this medical activity and to reveal their inherent limitations. The empirical basis of analysis includes 31 semi-structured interviews with healthcare professionals and inspectors, laws and regulations of the Russian Federation, and accessible statistical data on the state inspections of medical organizations. It was revealed that in this case the initial complexity of assessing the expert’s service by its customer is complemented by the lack of clear rules of expertise, the separation of control authority between different state bodies, the purely documentary nature of inspections, as well as severe but hardly applied sanctions for low-quality temporary disability examination. The main problem is that the external control system, focused on verifying the correctness of filling out the documentation, cannot track whether all patients with sick leaves were indeed incapable of working and the insured events did take place.