He served as chairman of the Conference of the German Bishops from 1987 to 2008, being considered one of the most influential prelates in Germany in those years and a leading proponent of liberal stances within the Church.

[2] He studied at the Seminary of Freiburg 1957–1964[3] and then at the Pontifical Gregorian University in Rome where he earned a doctorate in philosophy,[3] in 1962, with a thesis titled Vom Ursprung und Sinn der Seinsfrage im Denken Martin Heideggers.

[1] He also received a doctorate in theology in 1967, with a thesis titled "Auferweckt am dritten Tag nach der Schrift"—Exegetische und fundamentaltheologische Studien zu 1 Kor 15, 3b-5.

Working closely with CDU and Helmut Kohl, Lehmann favoured a compromise where abortion remained illegal, but under certain circumstances not punishable.

[11] The appointment came unexpected to many observers due to Lehmann's relatively liberal view on abortion counselling and giving eucharist to remarried parishioners.

About a dozen in number, they differed among themselves, but shared the view that Cardinal Joseph Ratzinger was not the candidate they hoped to see elected at the next conclave.

[14] Being considered a leading force for a more liberal Catholicism, he was called a bridge-builder, a man of dialogue and a "stroke of luck for German Catholics" by supporters, while Conservative critics derided the "Lehmann Church" as too accommodating to modern values.

The chairman of the German Bishops' Conference Reinhard Marx paid respect to Lehmann as a man who had influenced the Catholic Church globally.