Given that cyber technologies have made way for attempts to influence the affairs of other States in novel and unique ways, scholars have turned to the international legal rule which is prima facie most relevant in addressing such meddling; namely, the prohibition on intervention. Moreover, there appears to be quite a wide-ranging consensus in scholarship that the prohibition on intervention applies to a broad range of cyber operations. In contrast to such scholarship, this article argues that, under the lex lata, the prohibition on intervention only applies to acts amounting to a use of force or constituting support for the violent overthrow of a foreign regime. Nevertheless, a customary rule prohibiting a State from preventing the holding of an election in another State, or manipulating the vote tally thereof, may be close to crystallizing. The article first examines how the prohibition on intervention under customary international law was treated in its formative years—the 1960s to 1980s—finding that States could only achieve consensus that the use of force against another State, as well as support for the violent overthrow of a foreign regime, can amount to prohibited intervention. The article then dissects the International Court of Justice’s findings regarding the prohibition on intervention in the Nicaragua case—the leading case on the subject—concluding that it does not contradict that consensus. Finally, the article analyzes how the prohibition on intervention has been understood by States since the Nicaragua judgment, highlighting recent developments in States’ positions.