(CNN)Here is some background information about affirmative action as well as a few notable court cases.
Affirmative action policies focus on improving opportunities for groups of people, like women and minorities, who have been historically excluded in United States' society. The initial emphasis was on education and employment. President John F. Kennedy was the first president to use the term in an executive order.
Supporters argue that affirmative action is necessary to ensure racial and gender diversity in education and employment. Critics state that it is unfair and causes reverse discrimination.
Racial quotas are considered unconstitutional by the US Supreme Court.
The state of Texas replaced its affirmative action plan with a percentage plan that guarantees the top 10% of high-school graduates a spot in any state university in Texas. California and Florida have similar programs.
Timeline (selected cases)
1954 - The US Supreme Court, in Brown v. Board of Education, rules that the "separate but equal" doctrine violates the Constitution.
1961 - President Kennedy creates the Council on Equal Opportunity in an executive order. This ensures that federal contractors hire people regardless of race, creed, color or national origin.
1964 - The Civil Rights Act renders discrimination illegal in the workplace.
1978 - In Regents of the University of California v. Bakke, a notable reverse discrimination case, the Supreme Court rules that colleges cannot use racial quotas because it violates the Equal Protection Clause. As one factor for admission, however, race can be used.
1995 - The University of Michigan rejects the college application of Jennifer Gratz, a top high school student in suburban Detroit who is white.
October 14, 1997 - Gratz v. Bollinger, et al., is filed in federal court in the Eastern District of Michigan. The University of Michigan is sued by white students, including Gratz and Patrick Hamacher, who claim the undergraduate and law school affirmative action policies using race and/or gender as a factor in admissions is a violation of the Equal Protection Clause of the Fourteenth Amendment or Title VI of the Civil Rights Act of 1964.
December 3, 1997 - A similar case, Grutter v. Bollinger, is filed in federal court in the Eastern District of Michigan. Barbara Grutter, denied admission to the University of Michigan Law School, claims that other applicants, with lower test scores and grades, were given an unfair advantage due to race.
December 2000 - The judge in the Gratz v. Bollinger case rules that the University of Michigan's undergraduate admissions policy does not violate the standards set by the Supreme Court.
March 2001 - The judge in the Grutter v. Bollinger case rules the University of Michigan Law School's admissions policy is unconstitutional.
December 2001 - The Sixth Circuit Court of Appeals hears appeals in both University of Michigan cases.
May 14, 2002 - The Sixth Circuit Court of Appeals reverses the district court's decision in Grutter v. Bollinger.
January 17, 2003 - The administration of President George W. Bush files a friend-of-the-court brief with the Supreme Court, opposing the University of Michigan's affirmative action program.
April 1, 2003 - The US Supreme Court hears oral arguments on the two cases. US Solicitor General Theodore Olson offers arguments in support of the plaintiffs.
June 23, 2003 - The Supreme Court rules on Grutter v. Bollinger that the University of Michigan Law School may give preferential treatment to minorities during the admissions process. The Court upholds the law school policy by a vote of five to four.
June 23, 2003 - In Gratz v. Bollinger, the undergraduate policy in which a point system gave specific "weight" to minority applicants is overturned six to three.
December 22, 2003 - The Supreme Court rules that race can be a factor in universities' admission programs but it cannot be an overriding factor. This decision affects the Grutter and Gratz cases.
November 7, 2006 - The Michigan electorate strikes down affirmative action by approving a proposition barring affirmative action in public education, employment, or contracting.
January 31, 2007 - After the Supreme Court sends the case back to district court; the case