What is the test for in-court identification in a criminal case?

2 To be sure, there are instances in which potentially unconstitutional in-court identifications are permitted because a confrontation between the witness and the defendant had not been anticipated or arranged by the prosecutor. See, e. g., United States v. Gentile, 530 F.2d 461, 468 (2d Cir.) cert. denied, 426 U.S. 936, 96 S.Ct. 2651, 49 L.Ed.2d 388 (1976); United States v. Kaylor, 491 F.2d 1127, 1131-32 (2d Cir. 1973), modified on other grounds, 491 F.2d 1133 (2d Cir. 1974) (en banc), vacated on other grounds sub nom., United States v. Hopkins, 418 U.S. 909, 94 S.Ct. 3201, 41 L.Ed.2d 1155 (1974). But in the instant case, the prosecutor brought about the confrontation between witness and defendant.