Andrew Caldecott, representing the BBFC in the appeal, admitted that there is no evidence to suggest that violent computer games promote actual violence in those who play them.
However, Caldecott maintained that the jury is still out and that the game would not be given a rating.
"The research certainly achieves the objective of establishing that research does not demonstrate that there is a causal link. But what it certainly does not establish is that there is not [a link]," he said, according to Eurogamer.
"In a Utopian society you would have effective measures where over-18s could play what was suitable for them without being cluttered by the fact that minors will see them.
"But you cannot make classification decisions without regard to the social prevalence [of games]."
Caldecott added that the constant violence in the game is unsettling, as is the fact that humans are killed with everyday objects, rather than "aliens or griffins or Daleks" with magical weapons.
He also claimed that the immersive nature of video games requires special consideration because they are more likely than violent films to be watched without accompaniment.
Earlier in the hearings Geoffrey Robertson, representing Rockstar, launched a furious attack on attempts to deny the game UK circulation because of its content.
"Millions of gamers play videogames and no crime has ever been directly attributed to them," he said.
"There is no evidence that playing interactive video games leads to a propensity to act them out in real life. We wonder why Manhunt 2 has been singled out for special treatment."
Robertson was also disappointed at the amount of fuss the BBFC itself had made over the game.
"The [BBFC's] reputation is not at stake. If it was, we could show how, over the last century, they have been derided for some of the most stupid decisions in censorship history," he said. "But we are not going to go down that road."
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