The challenge to the Texas plan gained traction in part because the makeup of the court has changed since the last time the justices ruled on affirmative action in higher education in 2003. Then, O'Connor wrote the majority opinion that held that colleges and universities can use race in their quest for diverse student bodies.
O'Connor retired in 2006, and her replacement, Justice Samuel Alito, has shown himself to be more skeptical of considerations of race in education.
Texas automatically offers about three-quarters of its spots to high school graduates based on their class rank as part of what was called the "top 10 percent" plan under a 1990s state law signed by then-Gov. George W. Bush. Since then the admissions program has been changed so that now only the top 8 percent gain automatic admission.
Race is a factor in filling out the rest of the incoming class. More than 8 in 10 African-American and Latino students who enrolled at the flagship campus in Austin in 2011 were automatically admitted, according to university statistics.
In all, black and Hispanic students made up more than a quarter of the incoming freshmen class. White students constituted less than half the entering class when students with Asian backgrounds and other minorities were added in.
The university said the extra measure of diversity it gets from the slots outside automatic admission is crucial because too many of its classrooms have only token minority representation, at best. At the same time, Texas argued that race is one of many factors considered and that whether race played the key role in any applicant's case was impossible to tell.
The Obama administration, roughly half of the Fortune 100 companies and large numbers of public and private colleges that feared a broad ruling against affirmative action backed the Texas program. Among the benefits of affirmative action, the administration said, is that it creates a pipeline for a diverse officer corps that it called "essential to the military's operational readiness." In 2003, the court cited the importance of a similar message from military leaders.