The crimes committed by two notorious rapists were so "exceptionally serious" they should never be released, the Court of Appeal has heard.
Joseph McCann, 35, was given 33 life sentences at the Old Bailey in December for a string of horrific sex attacks on 11 women and children - one aged just 11 - during a 15-day cocaine and vodka-fuelled rampage.
Reynhard Sinaga, 37, was handed a life sentence at Manchester Crown Court in January after being convicted of more than 150 offences, including 136 counts of rape, committed against 48 men - although police have linked him to more than 190 potential victims.
At a hearing in London on Wednesday, Solicitor General Michael Ellis QC argued the pair should have been given whole life terms for their crimes, which he said were among "some of the worst and most violent that this country has ever witnessed".
Addressing five senior judges, including Lord Chief Justice Lord Burnett, Mr Ellis said McCann's catalogue of offending was of the "utmost gravity" and included the use of violence and a "desire to humiliate and degrade his victims".
He told the court the effect on his victims was "profound" and they had suffered "severe psychological damage" as a result.
These offences are among the most serious sexual offences ever seen in our courts.
The Solicitor General described Sinaga as "the most prolific sex offender the courts have ever seen".
The effect on his victims has been devastating and will remain with them for the rest of their lives.
Mr Ellis said a whole life term for each offender would be a "proper reflection" of their crimes and the "significant harm" caused to a large number of victims.
He argued there is "no hierarchy of seriousness, such that homicide must always rank above sexual offending" when courts consider sentencing.
Mr Ellis also argued that, if the court does not consider that whole life terms should be imposed, then the 30-year minimum terms handed to McCann and Sinaga should be increased.
The case is the first time two separate offenders' sentences have been challenged together as being unduly lenient.
Speaking outside court, Mr Ellis said: "We have never before had a case which has resulted in a whole life sentence which was not one of homicide.
"This would be a first but it is right in my view that these cases are considered as wholly exceptional.
"This is a case where the court is minded to hear the circumstances and the legal arguments to see whether a new precedent can be created for cases of this exceptional gravity."
Lawyers representing McCann and Sinaga argued that whole life terms are only imposed in the most serious cases of homicide.
They said that, despite the "extremely serious" nature of the pair's crimes, they could not be considered "on an equal footing with the very worst cases of murder".
Jo Sidhu QC, for McCann, said it is "perfectly conceivable" that he will never be released from prison in any event, but that it will be for the Parole Board to determine at the conclusion of his minimum term.
McCann carried out a series of sex attacks in London and the North West in April and May 2019, two months after the convicted burglar was wrongly freed from prison following "major failings" by probation staff.
He was found guilty in December of 37 charges relating to 11 victims, aged between 11 and 71, and was described by sentencing judge Mr Justice Edis as a "classic psychopath".
Sinaga - the UK's most prolific serial rapist - preyed on lone, drunk young men around nightclubs near his flat in Manchester, posing as a Good Samaritan who offered them a floor to sleep on or promised them more drink.
The Indonesian student drugged the men then filmed himself sexually violating them while they were unconscious, with many of his victims having little or no memory of the assaults.
Judge Suzanne Goddard QC, who sentenced him to a minimum of 30 years, described Sinaga as "an evil serial sexual predator" and a "monster".
The Court of Appeal judges are expected to give their decision at a later date.