June 28 1919 Treaty of Versailles and Protection of Jewish Minorities in Poland

Article 11.

Jews shall not be compelled to perform any act which constitutes a violation of their Sabbath nor shall they be placed under any disability by reason of their refusal to attend courts of law or to perform any legal business on their Sabbath. This provision however shall not exempt Jews from such obligations shall be imposed upon all other Polish citizens for the necessary purposes of military service, national defense or the preservation of public order. Poland declares her intention to refrain from ordering or permitting elections. Whether general or local, to be held on a Saturday, nor will registration for electoral or other purposes be compelled to be performed on a Saturday. 

Source: Treaty With Poland Treaty of Peace between The United States of America, The British Empire, France, Italy , Japan, and Poland signed at Versailles on June 28th, 1919 pages 11-13