The world is experiencing a lasting shortage of organ donations – a problem more severe in some countries than others. Literature on the matter argues that an explanation for this is the various legal default consent systems, and the importance put on the opinions of the family members regarding the donation question in case of sudden death. This paper establishes the causal inference between cadaveric organ donation rates and the French amendment of the public health code, of 2017, which limited the authorization given to the family members - aiming to decrease family refusal rates and consequently increase cadaveric organ donation rates. By applying the synthetic control method, a synthetic counterfactual to France is constructed from a donor group, including comparable European countries. The counterfactual, Synthetic France, resembles what would have happened in France in the absence of the amendment. The results show that the legal amendment of article L1232-1 in the public health code (code de la santé publique) was likely the driving force behind the increased donation rate in the subsequent years. The main finding of this study is robust and statistically significant, providing confidence to the claim of causal inference.