U.S. District Court Judge Bernice Donald has denied a stay of her July court order restarting the racial desegregation process in the Shelby County school system. In denying the stay, Donald ordered school leaders to appoint a special master by April 26 to oversee the desegregation process.

The school system and all other parties in the 45-year-old case sought in 2006 to have the school system declared a unitary system in which the goal of schools that weren’t racially identifiable had been met.

But Donald rejected unitary status on the issues of student assignments and faculty recruitment efforts. She also ordered a goal of having each county school reflect the racial makeup of the overall school district within 15 percentage points.

The first step toward coming up with such a plan is the appointment of a special master all sides agree on to oversee the effort.

County school officials and plaintiffs in the case have said the order would require the renewal of widespread court-ordered busing to achieve such a racial balance in the predominantly white school system.

The school system is appealing the ruling. But Donald ruled this week that the school system hasn’t met the standard of showing it is likely to win on appeal, which is needed to delay carrying out the court order.

“Defendant must recognize that plaguing its district is the existence of schools with substantially disproportionate racial compositions,” Donald wrote in her order. “A presumption against schools with substantially disproportionate racial compositions is warranted when the school exists in a system that has a history of segregation.”