Although in 1975 he joined the Polish United Workers Party, in 1978 he was one of the founders of the anti-government Free Trade Unions of the Coast (Wolne Związki Zawodowe Wybrzeża).In mid-1980 he organized the strike in Elmor, and took part in the creation of the Inter-Enterprise Strike Committee (Międzyzakładowy Komitet Strajkowy) and soon afterwards, together with Lech Wałęsa and others, of the NSZZ Solidarity itself (he was the vice chair of the Founding Committee of Solidarity).After martial law in Poland in December 1981 led to the arrests of many Solidarity members, including Wałęsa, Lis went into hiding and in underground became one of the leaders of the Temporary Coordinating Committee (Tymczasowa Komisja Koordynacyjna), which served as an underground leadership of Solidarity.He was arrested in June 1984, accused of treason but released half a year later after amnesty was given to many imprisoned Solidarity activists.He is currently CEO of a private firm, member of the Advisory Council of Freedom Union Party, and President of the Solidarity Centre Foundation.