Final answer:
A concurring opinion is written by a Supreme Court justice who agrees with the majority decision but has different reasons for their agreement.
Step-by-step explanation:
A document written by a Supreme Court justice expressing agreement with a majority opinion but for different legal reasoning is known as a concurring opinion.
When a Supreme Court justice votes with the majority but wants to express distinct or additional legal reasoning, the justice writes a concurring opinion. This type of opinion is significant because it offers insight into different legal interpretations and frameworks that still align with the court's ultimate judgment.
It stands in contrast to a dissenting opinion, which is written by justices who disagree with the majority outcome. By providing their individual reasoning in a concurring opinion, justices contribute to the legal discourse and can influence future cases and legal thought.