Two notorious rapists who committed "some of the worst and most violent" sexual offences in English legal history could spend the rest of their life in jail if senior judges decide they should be given whole life terms.
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 during a 15-day cocaine and vodka-fuelled rampage.
Reynhard Sinaga, 37, was also sentenced to life in January at Manchester Crown Court for a total of 159 offences, including 136 counts of rape, committed against 48 men - although police have linked him to more than 190 potential victims.
The Attorney General's Office referred the 30-year minimum jail terms handed to McCann and Sinaga to the Court of Appeal as "unduly lenient" earlier this year.
At a hearing in London on Wednesday, solicitor general Michael Ellis QC will argue that McCann and Sinaga should both have been given a whole life tariff for a litany of sexual offences, which are "some of the worst and most violent that this country has ever witnessed".
The hearing, which will test whether a whole life order can be imposed in non-homicide cases, will also be the first time two separate offenders' sentences have been challenged together as being unduly lenient.
Five senior judges - including the Lord Chief Justice Lord Burnett and the President of the Queen's Bench Division, Dame Victoria Sharp - are expected to hear the case over two days.
McCann carried out a series of sex attacks in London and the North West in April and May 2019, just 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 the 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".