Luke Mitchell was convicted of murdering Jodi Jones in 2003
The fact the jury in the Jodi Jones murder trial was told Luke Mitchell had 20 bottles of urine in his bedroom did not amount to a miscarriage of justice.
The Appeal Court in Edinburgh has been told the judge's speech to jurors at Mitchell's trial ensured they were not influenced by the unconnected evidence.
The Crown also said transcripts from a police interview did not show he had been a "bullying" victim.
Mitchell, 19, was jailed for life in 2004 for murdering 14-year-old Jodi.
A high-profile trial heard bottles of urine were found in Mitchell's bedroom when it was searched in July 2003 and taken away by the police.
Donald Findlay QC, representing Mitchell, earlier argued the evidence was "wholly irrelevant" and provided no "link, key or motive" to the crime.
John Beckett QC, representing the Crown, told Lords Hamilton, Osborne and Kingarth: "His explanation was that because he slept on top of a bunk bed it was more convenient to do that than to do anything else.
"It was to show that explanation was untrue. The new ones (bottles) came at a time when his position was that he was sleeping in the living room next to his mother, or something like that."
Mr Beckett argued the evidence was presented in anticipation the defence would attempt to show Mitchell had the bedroom of a "normal" teenager.
However, he claimed the direction of original trial judge Lord Nimmo Smith to the jury that it was not a court of "morality or social attitude" meant that Mitchell's "habit" would not feature in their final decision.
"It can't contribute to a miscarriage of justice because any possible prejudice was dealt with at the trial," he said.
The body of Jodi Jones was found on a footpath near her home
Mr Beckett also covered eight segments from a police interview with Mitchell that Mr Findlay raised objections about.
He argued that the dialogue, which included discussion of Mitchell's actions on the night Jodi was murdered, did not show signs of "pressure, trickery or bullying".
Mr Beckett claimed these sections of the interview did not tell the jurors anything they had not heard from other witnesses or direct evidence.
Mitchell is trying to overturn his conviction for the murder of his girlfriend Jodi in June 2003 when they were both 14-year-old pupils at St David's High School in Dalkeith, Midlothian.
Her naked and mutilated body was found in woods beside Roan's Dyke path, Dalkeith, on the night of 30 June 2003.
Trial judge Lord Nimmo Smith ordered Mitchell to serve at least 20 years before applying for parole.
The appeal hearing before Scotland's top judge, Lord Hamilton - sitting with Lords Osborne and Kingarth - continues.