The jury in the inquest of Diana, Princess of Wales must consider whether Henri Paul’s colleagues have “closed ranks” to try to dismiss suggestions that he drove drunk on the night of the crash.
The coroner Lord Justice Scott Baker said there is “an issue about what part, if any, alcohol played in the collision”.
CCTV images, including shots of Mr Paul tying up his shoelaces, may suggest that he was not drunk.
But it is “clear” that staff at the Ritz knew Mr Paul had been drinking before getting behind the wheel, the coroner said.
They had seen him drink at least two Ricard liqueurs, despite differing claims from the al Fayed publicity machine.
John Macnamara, Mohamed al Fayed’s former head of security, admitted lying in a television interview by saying that Mr Paul drank only “a pineapple juice” before the fatal crash.
The coroner told the jury: “You will ask yourself how reliable you find the evidence of the Ritz employees to be and whether there was an element of closing ranks.
“You will need to decide what weight to attach to the evidence that Henri Paul was a person who could consume alcohol without necessarily showing adverse signs and the experts’ evidence that some individuals have such a degree of tolerance to alcohol that they give the appearance of being sober.”
No-one can be certain of what Mr Paul did in the three hours before he was called back on duty.
Paparazzi have also claimed that he was drunk but their statements come only after French officials issued a release stating that Mr Paul was drunk.
The coroner said: “One might expect also some of them to mention it in their very early interviews if they had really noticed anything about Henri Paul’s condition.”
Mr al Fayed has always insisted that blood and other samples which showed that Mr Paul was three times the French drink-drive limit were faked.
Experts have also questioned the chain of custody about the samples, even suggesting that they may not have belonged to Mr Paul, the jury heard.