Who is Responsible for Advice Labels on Games?

AccUser asks: "So, I spent the day in the local hospital with my son after he suffered a seizure while we played a computer game (that shall remain nameless). The game was labeled as one for younger children, but had no warnings about photosensitive seizures on either the packaging or associated documentation, and I assumed that it would be a safe game for him to play. Many games (Halo and others) come with these warnings, and rightly so - I expected that any game that was a potential risk would indicate this. To be honest, all was fine until the final level, when there were a significant number of special lighting effects, and I guess this triggered the subsequent events. So, is the labeling of games to indicate risk of photosensitive seizures and other dangers mandatory, both in Europe and the States, and who is responsible for placing this information? Is it down to the distributor? The publisher? The developer?"