On 22 April 2015, the trial of Oskar Gröning began in the Court of Assizes at the State Court of Lüneburg. The court is considering the charge that Gröning - who lives in retirement in a small village in Lower Saxony, near Hannover - assisted in the murder of over 300,000 Hungarian Jews between 16 May and 11 July 1944.

By his own public admission, Gröning served in the Auschwitz concentration camp in the role of an accountant in the headquarters staff. After he joined the Waffen SS in 1941, his prewar qualification as bank teller made him more useful accounting for property taken from victims of the SS than in serving and probably dying at the front, and this is what he did at Auschwitz.

Taking the stand in his own defense, Gröning admitted his personal moral culpability for the camp's infamous activities - possibly a first in the history of Germany's postwar Nazi-era prosecutions - but declined to concede that his own duties constituted "assistance" in the genocidal project. Such judgment was, he said, up to the court to determine.

Most press accounts note that the Gröning case derives from the legal precedent of the Munich prosecution of John 'Ivan' Demjanjuk, who was convicted in 2011 of assisting the murder of almost 30,000 Jews during his service as a guard at the Sobibor extermination camp. Under a theory of criminal liability that I originally devised for that case, the court found that because Sobibor served but one function – the murder of all arriving Jews – and because historical evidence showed that every guard assigned there rotated over time through every phase of that activity, then every guard necessarily assisted in murder, even without any evidence of participation in a particular murder.

Oskar Gröning
Auschwitz survivor and plaintiff Eva Kor attends the trial of former Nazi death camp officer Oskar Gröning. Ronny Hartmann/AFP

After Demjanjuk, I extended the theory to men who served in the guard battalion at the Birkenau camp of the Auschwitz complex (Auschwitz II), and only at the time of the murder of the Hungarian Jews in spring-summer 1944. The indictment of Johann Breyer by the state prosecutor in Weiden (in northeastern Bavaria) tested this extension; a US district court in Philadelphia found Breyer extraditable from the US to Germany to face these charges in 2014 (Breyer died before extradition could be carried out.)

Now, the court in Lüneburg must decide if Gröning, a bookkeeper broadly responsible for processing personal property looted from the Jews brought to Auschwitz, is also criminally liable for assisting the murder of those whose property he counted. (I have had no professional connection to the Gröning case.) The only evidence to illuminate the circumstances of his work at Auschwitz in 1944, and the role he played in mass murder, is historical and indirect.

But judges are not historians. They are neither trained to assess historical documents as historians would, nor in possession of knowledge of all historical sources that might shape the facts in a legal matter. They do, however, possess sophisticated understanding of the forensic reliability of information and sources, and the determination of the relevance of information to the legal matters they assess.

Holocaust Memorial Day 2015: Archive footage shows liberation of Auschwitz concentration camp

'There will be those who wonder what use bringing middle or lower-level Nazis to justice is, when so many higher-ranked Holocaust perpetrators eluded justice completely, but ignoring their crimes because of the past failures of the German and Austrian justice systems is only adding more injustice, when the opposite is required, and is an insult to their victims.'

Read Nazi Hunter Efraim Zuroff's take on the Groening trial here.

In the case of Auschwitz, the sources are particularly diverse and widespread. Some relevant documentation created by the Nazis at the camp survived the war and is stored in an archive there. Related materials repose in archives in Russia, Ukraine, Poland and other countries. The testimony and witness statement material from previous German trials, including the important 1960s Frankfurt Auschwitz trials, is highly relevant, as are the judgments. An objective assessment of Gröning's culpability will depend on a comprehensive and synthetic analysis of all these sources.

The court in Lüneburg will therefore hear historical experts concerning the duties and responsibilities of Gröning at Auschwitz in spring-summer 1944. Among these experts will be Dr. Stefan Hördler, perhaps the world's leading expert on the concentration camp guard forces and their operation at Auschwitz.

The court has received from Dr. Frank Bajohr, a German expert on the Holocaust, a hitherto unknown wartime Nazi document (which he received from Dr. Hördler) that showed Gröning seeking authorisation to marry his dead brother's fianceé in late 1943. The document established that Gröning was serving at Auschwitz shortly before the Hungarian operation began. It is unclear, however, how it will assist the court to establish Groening's culpability as a member of the 4th Department of the headquarters staff at Auschwitz.

Was Gröning trying to avoid transfer to the front?

Because the defendant insisted to the court that his three requests for transfer out of Auschwitz ended in his commander's trash can, the new document seeking marriage might, to the contrary, suggest Gröning in fact had a strategem for avoiding transfer to the front (where SS units suffered particularly high casualties). This appears to be Dr. Bajohr's view, at least.

In past Nazi-era trials, a request for transfer to the front was always an acceptable defence (although no defendant ever had actually done that). Yet this demonstrates the dilemma of these trials. The court can fulfil expectations of "justice" and the establishment of historical truth only according to the formula that, the more the court depends on establishing the precise historical record, the more problematic will be the journey to judgment.

Finally, there is the question of forgiveness and "closure" for the victims and survivors. Already, one co-plaintiff has withdrawn following Gröning's admission of moral guilt. Public opinion in cases such as Gröning's naturally arouse strong views about accountability, contrition, and forgiveness. Indeed, the court traditionally pauses between the end of proceedings and the issuance of verdict to offer symbolic acknowledgement of those expectations.

Yet in the end, the court must weigh the evidence and issue its opinion on the basis of the law: is the evidence sufficient to judge the defendant? Indeed, the instrumentalisation of the hearing to literally bring moral questions to bear would be nothing less than the objectification of the defendant. The court in Lüneburg may face insurmountable dilemmas of a factual character in reaching a decision and so may, wisely, avoid delving into anything beyond Gröning's criminal liability for assistance in murder before the law.

Kirsten Goetze is a German jurist in Baden-Württenberg. She worked at the Central Office for the Investigation of National Socialist Crimes (Ludwigsburg) for five years. While there, she completed the investigations and recommended prosecution of cases against John Demjanjuk (Sobibor), Samuel K. (Blezec), Aleksej N. (Treblinka II), Johann Breyer (Auschwitz-Birkenau), and Osyp F. and Ivan K. (Ukrainian Police in Lwow), among others.