Actually, getting caught in a lie during an investigation severely impacts a witness' credibility. Even being mistaken about important points of fact without intentionally lying reduces witness credibility in the investigation phase. Intentionally lying while testifying in a court proceeding is perjury.
None of the above is grounded in what the law actually says or in legal, psychological or historical research regarding testimonies. California jury instructions state the following:
If you decide that a witness deliberately testified untruthfully about something important, you may choose not to believe anything that witness said. On the other hand, if you think the witness testified untruthfully about some things but told the truth about others, you may accept the part you think is true and ignore the rest.
So the law says that it is up to the jury to decide what to believe and what not to believe. This is clearly how things work in the real world.
It is true that a witness who is caught in an outright
lie will have their credibility severely damaged. But this is actually a rather uncommon occurrence for war crimes cases. One of the better known examples is Walter Petzold's testimony at the Frankfurt Auschwitz Trial, in which he claimed to have seen certain people in the vicinity of Krema I at the time of a crime being committed there; when the court walked the ground it found that Petzold could not have seen anything from his claimed vantage point, so his testimony was disregarded by the Frankfurt court.
Petzold was a 'green' and like many criminals, was evidently willing to exaggerate the extent of his direct knowledge. Hermann Langbein noted that there were other cases along the same lines; men who had undoubtedly been in Auschwitz and seen all manner of things, but who claimed to be direct witnesses of things they knew only from hearsay.
Indeed, the conflation of hearsay and direct witnessing is probably where one finds the greatest number of errors in testimonies from the camps. But it's often the case that it's deniers who ignore the difference and pretend that a hearsay witness is a direct witness.
Olga Lengyel, for example, never claimed to have set foot in the crematoria and reported totally inaccurate details about the number of muffles inside the crematoria. A number of denier authors jumped up and down about this, but since Lengyel was not claiming to have seen the muffles herself, she was merely repeating inaccurate hearsay. Her inaccuracy on this issue, which she could not have known from her own observations, doesn't impeach her credibility on the direct observations she does report, any more than Dogzilla being an ignoramus on virtually all the history of the Holocaust impeaches any direct observations he might testify to on this thread.
In the case of Lengyel and the number of muffles in the Birkenau crematoria, her inaccurate hearsay testimony isn't needed, since there are masses of documents as well as numerous direct witnesses who correctly testify to the right number. Her testimony becomes evidence of how such insider knowledge spread and was inevitably distorted among camp inmates, which is interesting to historians but of no legal consequence, and indeed her testimony wasn't given in court, but in a memoir.
If part of a witness' testimony is a lie and part of it is true the only way the true part would be believed is if it can proven independent of the untruthful witness' testimony. But if that were the situation, you wouldn't need that person's testimony because the points of fact would be proven by other means.
But this is precisely the situation in which courts constantly find themselves in 'normal' criminal cases. They have to decide based on conflicting testimonies given by prosecution and defence witnesses what happened. The most common outcome, of course, is that
the defendant is caught lying.
The other difference is between how things play out in court and how things play out in historiography.
In Nazi war crimes trials, the overwhelming majority of blatantly false testimony came from the defendants or defence witnesses. Eichmann undoubtedly lied about a variety of issues when he was interrogated, when he was cross-examined on the witness stand, and when he wrote his various memoirs. His testimony is not something one should rely on as an exclusive source to explain the course of events, because he manifestly had a motive to lie and obfuscate on some issues. Nonetheless, some historians have relied on Eichmann - most notably, Christopher Browning. Other historians have criticised Browning for this, but use the parts of Eichmann's testimonies which can be corroborated and confirmed.
Eichmann, as many will remember, testified that Heydrich summoned him one day and told him of a Fuehrer order to exterminate the Jews. We know there was a Fuehrer order to this effect from documentary sources referring to one retrospectively, and from other documentary sources which indicate that a Hitler order had just been given, most notably four sources from December 1941 (written materials from Goebbels, Frank, Rosenberg and Himmler)
Eichmann gave various dates for the time-frame in which he received Heydrich's order. Some of those dates can be seen to be backdated to exculpate Eichmann. On one occasion Eichmann said that he was informed by Heydrich in December 1941. That then fits with the documentary evidence. The other dates he gave fit with his defense strategy.
Now, we don't need Eichmann's testimony to date a Hitler order. But it is of some interest to learn how such an order was conveyed down the chain of command. Heydrich informing Eichmann is entirely plausible and pretty much what one would expect. There is no reason to disregard him on this point.
If Heydrich had summoned Eichmann to tell him of the impending Final Solution by resettlement, then Eichmann would have said so, since this would have exculpated him even more powerfully - and been in accordance with the desires of one of his interlocutors, the Dutch Nazi collaborator Willem Sassen. Sassen
wanted Eichmann to deny the Holocaust, but Eichmann didn't. That is a huge problem for deniers, of course, one you guys don't like to talk about very much and for which the denier collective has no credible explanation.
There is no reason to throw out the entirety of Eichmann's account because he was dissembling on a number of issues as a defence strategy (and to make himself look better in the eyes of posterity, a motive he himself admits), or because he changed his story depending on the dictates of the moment. The essential core account was already given as a free man outside of any interrogation cell or courtroom.
Eichmann's lies helped convict him in court. They don't exculpate him in the court of history, either. Nor does his testimony exculpate the Third Reich, or negate the reality of the Final Solution, or negate what extermination meant, since that is known from countless other sources.
So this is a very good illustration of the difference between 'falsus in uno, falsus in omnibus' and the more discriminating approach used in real-life courts and by real-life historians. If you know
why someone is lying, you can discount the effects of the lie, as long as you have other evidence to control for it.
Using part of a person's testimony that supports the narrative you're trying to establish while rejecting the bats**t crazy part of that person's testimony is called cherry picking.
If a witness gives
genuinely batcrap crazy testimony, then their whole account is usually disregarded.
The crux comes in defining what is genuinely "batcrap crazy". It's fairly clear that deniers have vastly different expectations and standards in this regard to normal sane people.
German lawyers are instructed that witness reliability and accuracy degenerates rapidly over quantifiable issues as well as some qualitative ones. Things like times, dates, durations, distances, quantities but even also colours are well known to be issues which are not remembered as precisely as 'brute facts'.
I'd estimate that the overwhelming majority of attempts by deniers to fuss-make over a particular witness testimony relate to quantitative issues. They can all be ignored as pointless wastes of time.
Truly 'batcrap crazy' would be Zisblatt.
It wouldn't be Gerstein exaggerating or overestimating the number crammed into a gas chamber. The brute fact of people being shoved into gas chambers at Belzec is confirmed by numerous other witnesses who don't claim exaggerated numbers.
Indeed one would absolutely expect a range of estimates from any group of witnesses asked to or volunteering information about numbers. So the sensible thing is to average them out and leave the data expressed as a range.
The stupid thing would be to seize on one estimated number alone and say it's fact, or to seize on one estimated number alone and say it's all untrue.
