The Republican-controlled State Assembly on Thursday approved a measure banning abortion after 20 weeks of pregnancy except in a medical emergency. The bill goes to Gov. Scott Walker for his signature. Mr. Walker, who is set to announce his candidacy for the 2016 Republican presidential nomination on Monday, will sign the bill into law, a spokeswoman has said. The bill, which makes no exceptions for pregnancies resulting from rape or incest, was passed by the Republican-led State Senate in June. It prohibits abortions 20 weeks after fertilization, when some abortion foes say an unborn child can experience pain. Twelve other states have similar bans, according to the Guttmacher Institute, which tracks the issue. The United States Circuit Court of Appeals for the Ninth District ruled in May that an Idaho ban on abortions after 20 weeks was unconstitutional.