Flawed electoral legislation in post-Soviet states facilitates the conduct of undemocratic elections. This paper argues that the low quality of electoral legislation in the region results in large part from a process of ‘authoritarian diffusion’, whereby the election laws of the post-Soviet states extensively borrow and adapt from existing Soviet and Russian laws. By contrast, the authorities of most post-Soviet states have routinely disregarded recommendations by the OSCE and the Venice Commission to improve electoral legislation. The paper points attention to a widespread but often overlooked form of institutional choice (legal borrowing and adaptation), presents evidence of ‘authoritarian diffusion’ across the post-Soviet area, and highlights the enduring impact of the Soviet legacy and of Russia’s relatively hegemonic position in the region.