Installed by the Nazis as leader of the Central Office of the Jewish Council of Elders in East Upper Silesia (German: Zentrale der Jüdische Ältestenräte Ostoberschlesien), responsible for some 45 Jewish communities of approximately 100,000 Polish Jews. Within a year, he controlled dozens of Judenräte.] Merin is noted to have been very harsh in his dealings with the Jewish groups opposing occupation including Hanoar Hazioni, Hashomer Hatzair, Gordonia, Poalei Zion, and Hitachdut. Merin aided the Nazis in the hunt for the leaders of the aforementioned groups, going so far as to place a request for their arrest and signing their execution orders himself.]He did this with full cooperation of the Jewish Police Force, whose leader fervently defended Merin’s every decision
Merin’s approach was similar to that of Chaim Rumkowski‘s, Judenälteste of the Łódź Ghetto, in that he was convinced that by tying the Jews in his ghettos to forced labor, some would survive the war. However, Merin engaged in extortions going far beyond what other ghetto leaders would ever attempt. On one occasion, Merin requested 15,000 zloty of ransom for each of the 100 prisoners he promised to free from the deadly slave labour. The amount was three-hundred-times higher than the highest similar ransom collected in the Lublin Ghetto. None of the Jews were released, and the money was never refunded. Like Rumkowski, Merin attempted to make justifications for the 25,000 Jews he helped to deport by claiming that their sacrifice enabled the survival of those who remained as he stated: “If I have lost only 25 percent when I could have lost all, who can wish better results?” It is because of his insistence on fulfilling every German request that Merin has been depicted as a Nazi collaborator.