A concurring opinion is a legal opinion written by a judge who agrees with the opinion reached by the majority in a case, but has different reasoning or would like to add something to the majority decision. Concurring opinions can be seen in legal cases where matters are tried in front of a panel of judges. These opinions cannot be used to set legal precedent and thus are of less interest in case law than majority opinions written to express the opinion of the majority of the court.
It is possible for several judges in a court to agree on a judgment for different reasons. Sometimes they reach a plurality opinion, agreeing as a group on the outcome of a case but on entirely different grounds. In these cases, all of the judges may write their own concurring opinions articulating the logic behind their opinions.
More commonly, a judge writes a concurring opinion to add to the majority opinion, or to indicate sections of the majority opinion that the judge does not agree with and articulate why. When a judge writes a majority opinion to represent the court, that judge may number the opinion so that it can be easily referenced. This allows a concurring judge to dispute particular sections in a concurring opinion, or to reference sections being expanded upon and explored in the concurring opinion.
Judges are not required to write concurring opinions, but they can be valuable and illuminating. Highlighting the parts of an opinion that may be topics of dispute can allow judges an opportunity to discuss the law more thoroughly. Such opinions may also be valuable for attorneys involved in the case, as they can learn more about the thought process involved in the court's decision. This information may be useful to have in the event of an appeal or an argument of a similar case before the same court.
Concurring opinions are a matter of public record and can be consulted by anyone with an interest in the outcome of a case. When they are cited in discussions, the fact that they are concurring opinions must be clearly noted so that readers understand the legal standing of the opinion being discussed. It is common to see “concurring opinion” in a shortened form such as “conc. op.” for the purposes of saving space when people are citing such opinions in legal briefs and other legal documents.