Nobles (defendant) was tried in federal court and convicted for robbing a bank. The only evidence linking Nobles to the crime was the identification testimony of a bank teller and salesman who were present at the time of the robbery. The defense tried to impeach these eyewitnesses and hired an investigator. This investigator interviewed both eyewitnesses and preserved some written notes. When testifying at trial, defense counsel used these notes to attempt to impeach the witnesses during cross-examination. With the bank teller, the defense asked if he remembered telling the investigator that he had seen only the back of the head of the person identified as the perpetrator. When he replied that he did not remember making that statement, he was allowed, despite the defense’s objections, to refresh his recollection by looking at a part of the investigator’s notes. The prosecution too was allowed to examine the relevant part of the notes. The witness then testified that although the report says that he saw only the back of the head, he still had seen more than that and insisted that Nobles was the robber. With the salesman, defense asked whether he remembered making the statement that “all blacks look alike to me.” After denying making this statement, the prosecution asked to see the document, defense objected, and the court refused the prosecution’s request. The court added that it would order disclosure of the document if the investigator testified concerning the witnesses’ alleged statements. Nobles called the investigator to the stand. The court said that a copy of the report (inspected and edited) would have to be submitted to the prosecution at the end of the investigator’s impeachment testimony. The defense refused to produce the report, and the court did not allow the impeachment testimony. The United States Court of Appeals for the Ninth Circuit said that the lower court decision was reversible error, and the United States Supreme Court granted certiorari.