RHYS Jones’s killer has had his hopes of freedom hit after another teen gun murderer lost an identical attempt to slash his own life sentence.
Junior Glasgow, who shot dead a lad the same year, mounted the “model prisoner” bid Mercer is trying but a High Court judge threw it out.
Glasgow had not been disciplined since 2013.
But we revealed last week Mercer, 29, had used an illicit iPhone to chat up a woman on the outside.
Gang member Mercer was 16 when he shot 11-year-old Rhys in Croxteth, Liverpool, in 2007.
Glasgow, of Brixton, South London, was 17 when he shot youth worker Nathan Foster, 18.
Both were sentenced in 2008, with Mercer getting 22 years and Glasgow 21.
Glasgow launched his bid for a tariff review last year under the same laws Mercer wants to use to edge closer to freedom.
But because the pair were juveniles when sentenced, they are able to apply for a review of their tariffs at the halfway point.
Court papers show Glasgow had finally admitted his guilt in 2017 and had held responsible jobs in jail.
MADDIE BREAKTHROUGHMaddie prime suspect revealed as German paedo living in campervan
HAIR & SQUAREHairdressers could reopen in two weeks with stylists in 'dentist-style' PPE
MADDIE CLUESHow prime suspect's mystery 30 min call led to new evidence in Maddie case
TENSION BOILS OVERUgly clashes at No10 after day's peaceful protest for Black Lives Matter
'HE GRABBED ME'Reporter screams on air as she is attacked by 'screwdriver-wielding man'
HELP US FIND HERWatch as Madeleine McCann cop appeals for help after breakthrough
He had also landed a string of qualifications, shown a "positive attitude", helped other cons "in crisis" and held "enhanced status" since 2016.
A psychologist also said Glasgow had "made excellent progress" in prison.
But Mr Justice Hilliard ruled out any tariff cut, saying Glasgow's progress needed "further testing" in prison first.