He was the only German judge who attempted to stop the mass-murder of persons deemed "unworthy of living" under the Aktion T4 "involuntary euthanasia" program, an intervention that cost him his job.

Lothar Ernst Paul Kreyssig was born in Flöha, Saxony, the son of a businessman and grain merchant.

In 1933, Kreyssig was pressured to join the Nazi party, but refused, citing his need for judicial independence.

[3] He reported his suspicions in a letter to Minister of Justice Franz Gürtner, dated July 8, 1940.

He also addressed the disenfranchisement of prisoners in Nazi concentration camps, making all his arguments on firm legal grounds.

However, in the Soviet occupation zone after the war, as an alleged Prussian Junker he lost part of his estate.

Feeling that the rule of law in the Soviet occupation zone was insufficient, Kreyssig decided against resuming his career as a judge.

In December 1950 the general synod of the Evangelical Church of the old-Prussian Union elected him its praeses, an office he held until 1970.

Kreyssig called for the founding of this action in 1958, saying that young Germans should go to former enemy countries and to Israel to ask for forgiveness and show, by volunteering to do good deeds to atone for the bombing and crimes of World War II and the Nazi regime (especially the Holocaust), to show signs of atonement, to work toward reconciliation, and for peace.

[1] The cities of Flöha, Brandenburg an der Havel, Magdeburg, Karlsruhe and Bergisch Gladbach each have a street named after him.

On the anniversary of his 100th birthday, a memorial plaque was unveiled at the Oberlandesgericht (Superior Regional Court) in Brandenburg an der Havel.

The former lower district court site, now the location of the Brandenburg Generalstaatsanwaltschaft (Attorney General), outside, has two memorial stelae and inside, a plaque with an inscription by Kreyssig's biographer, Konrad Weiß.

The Brandenburg Association of Jurists donated the plaque on 5 May 2008 to commemorate Kreyssig's Appeal to found the Action for Reconciliation on the 50th anniversary of its introduction.