Three men who were jailed for a plot to smuggle five tonnes of cocaine into the UK have been refused a chance to take their cases to the Supreme Court.
Russell Knaggs, 44, Phillip Hadley, 58, and Robert Rich, 46, were convicted of the conspiracy in 2012.
Ringleader Knaggs organised the scheme while serving a 16-year drug sentence in a Nottinghamshire prison.
The men claimed that evidence against them had been obtained by illegal email monitoring.
In an appeal hearing last December, lawyers for the trio questioned how prosecutors got their hands on email messages between the gang.
Their appeal was dismissed in August when judges led by Lady Justice Sharp said there was "no proper basis" for suggesting the emails were illegally obtained.
However, the men attempted to fight on by asking the court to grant permission to take the case to the Supreme Court.
They said the case involved a legal point of such importance that it should be decided by the country's most senior judges.
But Lady Justice Sharp returned to the Court of Appeal earlier to dismiss their application in a short ruling in London, saying the prosecution's case against them was "overwhelming".
Four members of the gang were convicted of conspiracy to import cocaine at two trials at Birmingham Crown Court in 2012.
Knaggs, of Conisbrough, near Doncaster, was jailed for 20 years; Hadley, of Humberston Fitties, near Cleethorpes, was sentenced to 18 years; and Rich, of Burton Road, Barnsley, was jailed for 14 years.
Another man also serving time in Lowdham Grange Prison alongside Knaggs was jailed for 16 years.
Colombian prisoner Jesus Anibal Ruiz-Henao, 57, was to use his connections to source the drugs.