The crisis that spurred the un to create an international law against genocide was the .

The correct answer is - the Holocaust.

The United Nations decided and voted for protection of the human rights and also the stopping of future genocides after the World War II ended, and on the basis of the terrors that happened in the Holocaust.

Because of the sufferings the Jews went through in this period, multiple laws were made in order to prevent something like this to ever happen again, and also, few years later, the Jews were in a way granted a country.

On the other side, it has to be said that the United Nations have been very subjective on this matter, as they have not taken in consideration the sufferings of the Gypsies and the Slavic people, and also genocides that have happened in front of their eyes like the genocide of the Turks over the Armenians, and the genocide of the Greeks over the Macedonians (also occupying their territory and giving their land to newcomers).