Lawyers for the man convicted of the 1988 Lockerbie bombing challenged on Wednesday the verdict of the judges in the original trial.
Defense lawyer William Taylor QC claimed that no "reasonable" jury would have found Abdelbaset ali Mohmed al-Megrahi guilty of the Pan Am Flight 103 bombing, in which 270 people died.
The appeal, which began on Wednesday, is being heard at the same venue as the trial, a specially built court at Camp Zeist in the Netherlands, the BBC reported.
The hearing is creating history by becoming the first British court proceedings to be televised live and streamed live on the Internet.
At the start of the hearing, the defense team issued a nine- page submission detailing their grounds for appeal.
Taylor told the five appeal judges he intended to show that the trial judges had effectively misdirected themselves as jurors and led to a miscarriage of justice.
He said he would be questioning the validity of parts of the written opinion and intended to bring fresh evidence which cast doubt on the conviction.
Al-Megrahi was sentenced to life imprisonment with a minimum of 20 years when the trial ended on January 31, 2001.
His co-accused, Al Amin Khalifa Fhimah, a former station manager for Libyan Arab Airlines, was acquitted after the judges ruled there was no evidence he had helped plant the bomb.
The panel of five judges hearing the appeal is headed by Lord Cullen, the Lord Justice General, who has presided over several high-profile public inquiries.
Taylor said he would argue that the verdict reached by the original court was not one that a reasonable jury in an ordinary trial could have reached if it was given proper directions by the judge.
According to the prosecution's version of events, which was accepted by the three trial judges, the suitcase carrying the bomb which blew up the plane was loaded onto a plane in Malta. From there it was transported via Frankfurt to Heathrow, where it was loaded onto Pan Am flight 103.
Al-Megrahi's defense team has always insisted the bomb suitcase was more likely to have been placed on board the plane at Heathrow and wants to introduce new evidence to support that claim.
It wants to hear fresh testimony from security guard Ray Manly who has claimed there was a break-in at the baggage build up area at Heathrow Airport on 21 December 1988, the same day Pan Am Flight 103 took off from there bound for America.
The defense will also launch a fresh attack on the evidence of Tony Gauci, a Maltese shopkeeper who identified al-Megrahi as a man who had bought clothing at his store a few weeks before the bombing.