Mitchell was 14 when he committed the murder and 16 when he was convicted
Judges have heard an appeal by convicted murderer Luke Mitchell to have his sentence reduced.
The 21-year-old was sentenced to life, with a minimum jail term of 20 years, after he was found guilty of murdering his girlfriend Jodi Jones in 2003.
A previous appeal against his conviction was refused in 2008.
The latest appeal for a reduced sentence was made on the basis that Mitchell was only 14-years-old when he committed the murder.
His counsel, Gordon Jackson QC, said: "My question is whether or not as a society we wish to say to a child for what you did as a child we won't even look at your case again for 20 years.
"The question is whether a civilised society should give children sentences like that?"
Both Mitchell and Jodi Jones were 14 at the time of the murder and Mitchell was 16 when convicted.
The appeal for a reduced sentence came after the judges rejected an appeal against the actual conviction.
The defence counsel pointed out that any decision to free Mitchell would ultimately be made by the parole board and he might never be released.
The three appeal judges will make a ruling on Mitchell's sentence appeal at a later date.