After the death of his father in 1863, he interrupted work on his habilitation and supported his mother in the education of his youngest sibling and the family tea trading business.
At the initiative of Bishop Blum, in 1869 Lieber gave his first speech at a Katholikentag (conference of Catholic laity).
During the Kulturkampf, he distinguished himself as an eloquent opponent of Bismarck, particularly in the debates on the National Sunday rest, the restriction of women, and child labor, and the general working time limit.
Following the partial withdrawal of the Kulturkampf laws, the party under his leadership struck a decidedly a national course.
Pope Leo XIII gave him the Grand Commander's Cross of the Order of St. George and made him a papal chamberlain.