1783: when the revolutionary
war ended, britain gave up
territory to the u. s. shade the
area south of the great lakes and
east of the mississippi.

Which statement best explains why a supreme court opinion is a seminal document? an opinion can become quite lengthy, which makes it a seminal document. supreme court documents are the only seminal documents in the united states. an opinion may create major changes in the laws or policies of the united states. generally speaking, a supreme court opinion reflects the feelings of all americans.