The McMartin Preschool Trial was a famous legal case in the United States in the 1980s. It involved seven people who ran a preschool were accused of abusing children in their care. The trial lasted more than seven years and was the longest and most expensive criminal trial in US history. The trial ended without any convictions as the jury could not agree on whether the accusations were true or false. Even though the trail was unsuccessful, it brought attention to the issue of child abuse and helped lead to better protection for children in the US.