Green (defendant) was charged with felony offenses related to the sale of marijuana. Green was charged on the basis of statements made to an undercover police officer by Porter. The state called Porter to testify at Green’s preliminary hearing. The state called Porter as a witness again during Green’s trial. When Porter gave testimony that conflicted with his testimony at the preliminary hearing, the prosecution introduced excerpts from the preliminary hearing. The prosecution also called a police officer to testify about Porter’s initial statements to police. Green was convicted. The state supreme court had previously held that prior statements of a witness could not be admitted as evidence if the statements had not previously been subject to cross examination. In Green’s case, the state supreme court applied the same ban to Porter’s preliminary hearing testimony. The state of California (plaintiff) petitioned the United States Supreme Court for review.