Legal Research: KeyCite

When a court decides a legal question, it creates a precedent. Unless a higher court or new legislation reverses the decision, the court’s decision has the effect of law. Court opinions are written to explain the Court’s decision. Research tools have been developed to assist someone who is doing legal research to determine if a Court’s opinion has been reversed by a higher court or legislation. Westlaw’s system is called KeyCite. Lexis\Nexis and Nexis Uni have a similar tool called Shepard's. When completing a legal research project you must use either KeyCite or Shepard's to determine if the court opinions you are relying upon to answer a legal question have not been overruled, distinguished or limited in some manner.

Keycite Flags

• Red Flag - Severe Negative Treatment (This is opinion is no longer good law. At least one of the points of law it contains has been overruled by either legislation or a higher court. The legislation or higher court opinion which overruled the opinion will be displayed next to the opinion. This opinion should not be used.)
  • Ex: Roe v. Wade 410 U.S. 113 (1973), 93 S.Ct. 705, 35 L.Ed. 2d 147.
• Yellow Flag - Some Negative Treatment (Some parts of the legal reasoning in this opinion have either been overturned, distinguished or limited by either legislation or higher court decisions. Subsequent cases may have further refined the legal reasoning in this case distinguishing it. By far, most cases you come across will be yellow flagged. Yellow flagged cases require further research to determine which part of the case is still useable and which may have been overturned, distinguished or limited. See the Negative Treatment Tab.
  • Ex: Miranda v. Arizona 384 U.S. 436 (1966), 86 S.Ct. 1602, 16 L.Ed. 2d 694.
• Please see the "Keycite on Thomson Reuters Westlaw" link in the box on the lower right for more information on Flags and the KeyCite service.

Always use the Negative Treatment Tab to locate other cases that have either overturned, altered or distinguished the legal reasoning of the case you are currently viewing. Note that cases in the Negative Treatment Tab may only deal with one legal question presented in the case that you are currently viewing and may not effect the legal issue you are researching. It is important to review all the cases that might have a negative bearing on the case that you are reviewing. It is also important to recognize the jurisdiction of cases with negative treatment. Court case opinions from other legal jurisdictions (other states) may not effect the precedent value of the case you are viewing.

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