Describing the circumstances of the alleged assault as "matters of physical improbability to the point of impossibility," Pell's lawyer also said the inconsistency in the dates of Pell's alleged crimes points the weakness of his conviction.
Prosecutors initially charged that the assault might have happened sometime between Pell's installation in August of 1996 and the end of December of the same year, but during the trial evidence left only two dates for the jury to consider: December 15 or 22, 1996, the first two occasions when Pell celebrated Sunday Mass in the cathedral.
Walker then drew the judges' attention to prosecution attempts to introduce a third possible date during the appeal process, suggesting November 3 as a possibility, calling it an indication that prosecutors did not believe their own arguments.
"The notion that on appeal the unsafe and unsatisfactory nature of a verdict on a case put to the jury of either the 15 or 22 of December can or should be answered or rehabilitated by a distinctly new case [for] 3 November being advanced is in itself disturbing, should disturb this court."
Walker argued that even though the prosecution had withdrawn the argument suggesting November 3 as a possibility, "it is an appropriate reflection, forensically manifested by the Crown, of the doubts to which I am going to speak, involved in the theory that this supposed first incident indeed took place on the 15 or 22 December – and if it didn't take place on one of those two dates then the Crown case fails."
"Date is important," Walker said. "Pell was appointed in July, installed in August, but didn't say his first Sunday high Mass at the cathedral until 15 December."
The defence also argued that, on whatever Sunday the assault was supposed to have taken place, the circumstances of the allegations did not add up.
According to the narrative of the alleged victim and sole witness, the alleged abuse had to take place after Sunday Mass, at which Pell had presided and for which he was still fully vested.
Walker argued that witness accounts of Pell's public visibility after Mass meant that for him to have assaulted the two teenagers for a period of 5-6 minutes alone in the sacristy was "literally and logically impossible according to the complainant's account," and that there was no other account offered of the alleged abuse.
The difficulty in establishing a possible date for the alleged offense, together with witnesses who testified to Pell's visibility after Mass, meant, Walker said, that the prosecution case could not mount a credible claim to being beyond reasonable doubt.
"If you have to be, for the offending, in a particular place in a particular time, then credible evidence, never challenged, places the archbishop in a position carrying out an activity at a time rendering the offending, according to the complainant's account impossible, or put more softly simply not a realistic possibility."
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Walker also presented several other lines of argumentation that he said showed the weakness of the prosecution's case and the failure of investigators to call or interview material witnesses.
He specifically argued that the alleged date for a second offense by Pell was unsupported by even the alleged victim's testimony and had been chosen simply as "the next time the prosecution could suggest that the Archbishop was at Sunday Mass in the cathedral."
The defense also argued that the jury had been effectively invited consider the alleged victim as credible, despite the defense being unable to test his credibility in court. It was, Walker said, impossible to raise a reasonable doubt about evidence which could not be properly subjected to in person cross-examination.
Pell, who was present in court, turns 78 this week. The hearing is set to continue throughout Wednesday and Thursday. The judges could deliver their verdict at any point during the two days, or reserve their judgement to a later date.