Judges have been urged to rule that a 15-year jail sentence given to a surgeon who carried out needless breast operations was "unduly lenient" and should be increased.
Ian Paterson, 59, from Altrincham, Greater Manchester, who left victims scarred and disfigured, watched proceedings via video-link from prison as three Court of Appeal judges heard argument that his current sentence was "not sufficient" to reflect the seriousness and the totality of his offending.
Paterson was sentenced to a total of 15 years in May following a trial at Nottingham Crown Court.
Lady Justice Hallett, Mrs Justice Carr and Mr Justice Goss are reviewing the sentence at a hearing in London after it was referred to the court by Solicitor General Robert Buckland.
Mr Buckland argued on Thursday that Paterson's offending was "so serious and so exceptional" that a jail term "significantly higher" than 15 years was required.
It would merit a sentence of around 20 years - or even higher, he suggested.
Mr Buckland said the surgeon's crimes had "caused a very high degree of physical and psychological harm" to vulnerable patients.
Paterson was convicted by a jury of offences of wounding with intent and unlawful wounding against 10 patients.
Sentencing him to a total of 15 years, Mr Justice Jeremy Baker told Paterson: "You deliberately played upon their worst fears, either by inventing or deliberately exaggerating the risk that they would develop cancer, and thereby gained their trust and confidence to consent to the surgical procedures which you carried out upon them.''
His trial heard evidence from nine women and one man who were treated in the private sector at Little Aston and Parkway Hospitals in the West Midlands between 1997 and 2011.
Victims told the court that Paterson's crimes had left them in constant pain and struggling to trust medical professionals.