What impact did the Holocaust have on the Jewish and Roma populations of Europe?

It had an enormous impact on the two populations.

Explanation:

Calculations estimate that approximately 6.5 million European Jews were exterminated during the Holocaust, which was approximately two thirds of the European Jewish population.

Again estimates of Roma deaths because of the Holocaust are between 250,000 and 500,00 out of an estimated 1-1.5 million.

a case involving the laws of a single state.