The US video game industry sued the state of Minnesota on June six to overturn a new law that imposes $25 fines on children under the age of 17 who rent or buy video games aimed at adults.
The Entertainment Software Association said the law - which marks the latest skirmish between the industry and US states over content in video games - violated free speech protections in the US constitution.
"The state is attempting to impose liability on children because they know that the courts have consistently held that they cannot penalise retailers," the group said in the lawsuit filed in federal court in Minnesota.