The highest court in the US is considering whether children can be stopped from buying violent video games.
The Supreme Court case centres on a ban in California on selling or renting games to those under the age of 18.
Opponents of the measure says it breaches the First Amendment guarantee of freedom of speech.
But supporters say the law is necessary as violent games can cause harm to children.
The California prohibits the sale of violent video games to children "where a reasonable person would find that the violent content appeals to a deviant or morbid interest of minors, is patently offensive to prevailing community standards as to what is suitable for minors, and causes the game as a whole to lack serious literary, artistic, political, or scientific value for minors".
After a legal challenge by industry groups, a district court and then the court of appeals stopped the law coming into effect.
The Supreme Court may have to decide if California is required to demonstrate "a direct causal link between violent video games and physical and psychological harm to minors" before stopping games being sold to them.
Outgoing California Governor Arnold Schwarzenegger is supporting the legal case against the Entertainment Merchants Association, with a number of other trade groups and rights activist bodies involved.
Under the California law retailers would be fined up to $1,000 (£625). If an adult bought the game and gave it to a minor that would not be an offence.
There is already a nationwide voluntary system of game classification.