Busing for large-scale desegregation (the elimination of separation of the races) began in 1971, when the U.S. Supreme Court decided that many school districts had not complied with the 1954 Brown v. Board of Education of Topeka decision. Once the charter has been approved for operation and staff has been hired, the charter can begin enrollment and operations. Because charter schools are schools of choice, students apply to enroll in charter schools. Like traditional public schools, charter schools cannot discriminate against students in enrollment – for example, a charter school cannot require students to pass a certain exam or be from a certain religious or racial background in order to enroll. If more students apply for the charter school than the school’s capacity, students will be entered into an admissions lottery that chooses students using a system of randomization.