A juror jailed for researching a defendant's past on the internet has been refused permission to appeal.
Ex University of Bedfordshire academic Dr Theodora Dallas told jurors a man on assault charges at Luton Crown Court had previously been accused of rape.
Earlier this week Dallas, who is from Greece and had claimed her English is "not that good", was jailed for six months for contempt of court.
Dallas sought permission to appeal to the Supreme Court but this was refused.
The academic, who came to England at the age of 19, caused the trial of Barry Medlock to be abandoned last July.
She carried out internet research and told other jurors that Medlock, who was on trial for assault occasioning grievous bodily harm with intent, had previously been accused with rape - a charge of which he was acquitted.
Three Supreme Court justices - Lord Phillips, Lord Hope and Lord Kerr - refused her permission to appeal saying that her case did not raise "an arguable point of law".
At the contempt hearing, judges heard claims that Dallas's grasp of English was sometimes "not that good".
She was told that she would serve three months in jail and be on licence for the remainder of the term.
Lord Judge said Dallas had "deliberately disobeyed" the trial judge's instructions not to search the internet and added: "The damage to the administration of justice is obvious."