There are several types of opinions:

  • Majority opinions are issued when at least five justices agree with the legal reasoning behind the decision. These opinions form new precedents that lower courts must follow.
  • Plurality opinions are issued when several justices agree with the decision but not the legal reasoning behind it. A plurality opinion represents the views of a majority of the justices on the winning side.
  • Concurring opinions are issued by justices who agree with the winning side but disagrees with the legal reasoning.
  • Dissenting opinions are issued by justices who opposed the ruling decision and favored the losing party in a case. Dissenting opinions explain why the dissenting justices find the ruling decision wrong.

The decision can affirm the lower court’s ruling, in which case that ruling stands. If the Supreme Court finds error in the lower court’s ruling, it can reverse the ruling. Sometimes when a case is reversed, it gets remanded, or sent back to a lower court for a new trial or proceeding.

The following table summarizes some of the most important court cases in American history.





Marbury v. Madison1803Courts assumed the power of judicial review (the power to declare laws unconstitutional)
McCulloch v. Maryland1819Granted the federal government broad powers through the necessary and proper clause
Dred Scott v. Sanford1857Forcibly returned a slave to his owner in the South and thus increased tensions over slavery
Plessy v. Ferguson1896Ruled that “separate but equal” was constitutional; legalized segregation and Jim Crow laws
Brown v. Board of Education1954Overturned Plessy; declared segregation unconstitutional
Mapp v. Ohio1961Expanded the exclusionary rule to cover state courts
Gideon v. Wainwright1963Ruled that the government must supply a lawyer to those who cannot afford one
Miranda v. Arizona1966Ruled that police must inform people they are about to question of their right against self-incrimination
Roe v. Wade1973Legalized abortions in the first trimester of pregnancy
Bush v. Gore2000Decided the 2000 presidential election by ruling that the Florida Supreme Court was wrong in ordering a recount

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