By Caroline Briggs
BBC News entertainment reporter in Cannes
Cannes festival head Gilles Jacob has called for this year's top prize to be awarded for film-making, not politics.
Cannes jury president Emir Kusturica with actress Salma Hayek
Last year, the festival brought Michael Moore's Fahrenheit 9/11 to global attention when it won the Palme d'Or.
The 58th festival is the world's most prestigious gathering of the film industry and starts Wednesday.
The event opens with a gala screening of Lemming, a surreal family drama starring Charlotte Gainsbourg and British actress Charlotte Rampling.
"Michael Moore's talent is not in doubt," said director Gilles Jacob, referring to the film-maker's win at Cannes in 2004.
"But in this case, it was a question of a satirical tract that was awarded a prize more for political than cinematographic reasons, no matter what the jury said."
He added that the jury's acclaim for Michael Moore's documentary was an "out of the ordinary event that probably won't be repeated".
Cannes film festival attracts more than 40,000 movie industry workers and members of the film industry every year.
The festival jury will pick the winner of the prestigious Palme d'Or prize, as well as six other awards, from the 20 films entered in the competition.
Jury president Emir Kusturica said they would judge films on their "aesthetics" when choosing this year's winners.
Bosnian-born director Kusturica - who won the festival's top prize in 1985 and again in 1995 - said it would be a "decision of the heart, helped by rationale".
There are 20 films in competition for the prestigious Palme d'Or
Kusturica is joined on the nine-strong panel by actress Salma Hayek, Spanish actor Javier Bardem and Nobel laureate in literature Toni Morrison.
Kusturica said it would be difficult for the jury to select the Palme d'Or winner.
"It is very difficult for me to be democratic as the nature of cinema is not very democratic," he said. "There is consensus, but there is not a democracy."
Hayek added that she found it "much more exciting" to attend Cannes as a jury member than as an actress.
"When you come to a festival with a movie, most of the learning has been done and you are just presenting it," she said.
"But when you are a juror, it is in the moment that the visual stimulation is reached because you get to see so many movies and you push yourself to understand them."
The jury also includes Face/Off director John Woo, Indian actress Nandita Das, French directors Agnes Varda and Benoit Jacquot and German film-maker Fatih Akin.
Speaking ahead of the opening film on Wednesday, star Charlotte Rampling called film-making in Europe less "barbaric" than Hollywood for ageing actress.
Rampling, 60, is currently filming the sequel to Basic Instinct
"The system in Europe is not like Hollywood. It is not as barbaric," said the 60-year-old actress. "The fact that you have a few wrinkles is not a reason to be put away."
"In Europe, thank goodness, they have realised that and I'm still here".
Lemming is being screened in competition, alongside new works from Gus Van Sant, David Cronenberg and Denmark's Lars von Trier, and is considered one of the forerunners for the prestigious Palme d'Or.
Describing the film as "dark, but not pessimistic", director Dominik Moll said he didn't know why it had been chosen to open the festival.
"I was surprised because usually it is a more commercial film that is not in competition," he said.
"Maybe the organisers wanted to get into the heart of the competition straight away."