"The Assembly was over. Delegates shook hands hastily with one another and disappeared into the winter mists of Paris. The same night I went to bed with fever. I was ill and bewildered. The following day I was in the hospital in Paris... Nobody had established my diagnosis. I defined it... as Genociditis: exhaustion from the work on the Genocide Convention."

In 1946, Lemkin turned to the United Nations (UN) General Assembly convened at Lake Success, NY in an effort to have the newly formed body condemn the act of genocide as an international standard. He presented a draft resolution for a Genocide Convention treaty to Cuba, India, and Panama, persuading them to sponsor the resolution. He also formed a committee to lobby 23 organizations around the world, which resulted in a joint petition supporting the adoption of a Genocide Convention, and which was presented to the delegates of the General Assembly.

The final draft of the resolution was approved by the General Assembly on December 11, 1946. It affirmed that genocide was a crime under international law and directed the Member States and the Social and Economic Council to draft a treaty to present to Member States for ratification.

From 1947-1948, the Convention on the Prevention and Punishment of the Crime of Genocide was hashed out with Lemkin's consultation. The draft was presented to the General Assembly from September to December 1948 at the Palais de Chaillot in Paris and was unanimously adopted on December 9, 1948.