In 1918 Shumsky was elected to the Ukrainian Constituent Assembly from the Volhynian Governorate. He also became one of authors of the Law of Ukraine about land adopted by the Ukrainian Central Council on 18 January 1918. On Shumsky was arrested after he with a group of left Ukrainian SRs and Social-Democrats attempted a coup-d'état to dissolve the parliament (see January Uprising), but was freed by advancing Red Russian detachments of the Muravyov's troops which eventually sacked Kiev.