MADISON, Wis. (AP) — Republican Gov. Scott Walker has signed a bill that legalizes the use of a marijuana byproduct to help treat children's seizures. The bill allows the use of cannabidiol, an oil extract, to be administered under the care of a doctor. The measure falls far short of legalizing the use of marijuana for medical purposes. The Assembly passed the bill on a voice vote in March. The Senate passed it unanimously earlier this month. Walker's office released a statement Wednesday saying he had signed the bill along with 54 other measures at the state Capitol.