Glover, an undercover officer, and Brown, an informant, went to an apartment building for the purpose of purchasing narcotics from 'Dickie Boy' Cicero, a known narcotics dealer. Glover knocked at the door of one of the two apartments served by the stairway. The area was illuminated by natural light from a window in the third-floor hallway. The door was opened 12 to 18 inches in response to the knock. Glover observed a man standing at the door and, behind him, a woman. Brown identified himself. Glover then asked for 'two things' of narcotics. The man at the door held out his hand, and Glover gave him two $10 bills. The door closed. The man returned and handed Glover two glassine bags. Glover stood within two feet of the person from whom he made the purchase and observed his face. Five to seven minutes elapsed from the time the door first opened until it closed the second time. The transaction took eight minutes. At headquarters, Glover described the seller to other officers. Glover at that time did not know the identity of the seller. He was 'a colored man, approximately five feet eleven inches tall, dark complexion, black hair, short Afro style, and having high cheekbones, and of heavy build. He was wearing at the time blue pants and a plaid shirt.' An officer obtained a photograph of Brathwaite (D) and left it at Glover's office. Glover, when alone, viewed the photograph for the first time upon his return to headquarters. He identified the person shown as the one from whom he had purchased the narcotics. The bags had heroin in them. D was arrested on July 27. The photograph from which Glover had identified D was received in evidence without objection on the part of the defense. Even after 8 months, Glover testified that there [was] no doubt whatsoever' in his mind that the person shown on the photograph was D. Glover made a positive in-court identification without objection. No explanation was offered by the prosecution for the failure to utilize a photographic array or to conduct a lineup. D testified that he was at the doctors when the alleged crime was to have taken place. D was convicted, and it was affirmed by the Supreme Court of Connecticut. D then filed a petition for habeas corpus. He alleged that the admission of the identification testimony at his state trial deprived him of due process of law to which he was entitled under the Fourteenth Amendment. The petition was dismissed. The Second Circuit reversed, with instructions to issue the writ unless the State gave notice of a desire to retry respondent and the new trial occurred within a reasonable time to be fixed by the District Judge. The court felt that evidence as to the photograph should have been excluded, regardless of reliability, because the examination of the single photograph was unnecessary and suggestive. The Supreme Court granted certiorari.