I
The equal right of the prosecution and the defense in criminal proceedings to interview witnesses before trial is clearly recognized by the courts. United States v. Scott, 518 F.2d 261, 268 (6th Cir. 1975); United States v. Matlock, 491 F.2d 504, 506 (6th Cir.), cert. denied, 419 U.S. 864, 95 S.Ct. 119, 42 L.Ed.2d 100 (1974); Callahan v. United States, 371 F.2d 658, 660 (9th Cir. 1967). No right of a defendant is violated when a potential witness freely chooses not to talk; a witness may of his own free will refuse to be interviewed by either the prosecution or the defense. United States v. Scott, supra at 268; Byrnes v. United States, 327 F.2d 825, 832 (9th Cir.), cert. denied, 377 U.S. 970, 84 S.Ct. 1652, 12 L.Ed.2d 739 (1964). However, when the free choice of a potential witness to talk to defense counsel is constrained by the prosecution without justification, this constitutes improper interference with a defendant’s right of access to the witness. Justification on the part of the prosecution to interfere with that right can be shown only by the clearest and most compelling considerations. Cf. Dennis v. United States, 384 U.S. 855, 873, 86 S.Ct. 1840, 1850, 16 L.Ed.2d 973 (1966).
Appellants’ claim that governmental interference with their access to witnesses during the investigative stage preceding the state court trial denied them due process of law presents the limited issue whether they received in the state court an essentially fair trial in the federal constitutional sense. “As applied to a criminal trial, denial of due process is the failure to observe that fundamental fairness essential to the very concept of justice. In order to declare a denial of it we must find that the absence of that fairness fatally infected the trial; the acts complained of must be of such quality as necessarily prevents a fair trial.”
Lisenba v. California, 314 U.S. 219, 236, 62 S.Ct. 280, 289, 86 L.Ed. 166 (1941). Cases which have held that the defendant was denied due process when his access to witnesses before trial was obstructed by the prosecution follow:
Gregory v. United States, surpa at 188;
United States v. Tsu-tagawa, 500 F.2d 420 (9th Cir. 1974);
United States v.
Mendez-Rodriguez, 450 F.2d 1 (9th Cir. 1971);
Hernandez v. Nelson, 298 F.Supp. 682 (N.D.Cal.1968),
aff’d, 411 F.2d 619 (9th Cir. 1969). The issue of prosecutorial interference with witnesses was raised in the cases which follow, and the courts for various reasons declined to find that defendant’s right to a fair trial was violated.
United States v. Nardi, supra; United States v. Cook, 608 F.2d 1175 (9th Cir. 1979),
cert. denied, 444 U.S. 1034, 100 S.Ct. 706, 62 L.Ed.2d 670 (1980);
Salemme v. Ristaino, 587 F.2d 81 (1st Cir. 1978);
United States v. Hyatt, 565 F.2d 229 (2d Cir. 1977);
United States v. Jones, 542 F.2d 186 (4th Cir.),
cert. denied, 426 U.S. 922, 96 S.Ct. 2629, 49 L.Ed.2d 376 (1976).
Mindful that a defendant, when claiming improper denial of access to a potential witness on due process grounds, must make a showing of more than merely the witness’ inaccessibility, United States v. Scott, supra at 268, we turn to examine the record as a whole to assess the effect on the state court trial of the improper instructions given by the state trooper. A summary of the relevant facts and procedural history follows. On August 24, 1976, shortly before 2 P.M., William Reilly, an inmate at M.C.I. at Walpole occupying a cell on tier one of block ten, suffered injury when the open solid steel outer door of his cell was slammed against his left arm extended through the locked inner grille door. He had been assigned to the cell the preceding day. He was taken to the Lemuel Shattuck Hospital where he underwent an operation. A day or two later, he gave a written statement to the state trooper, the chief investigating officer for the Commonwealth, identifying the appellants as the men who had assaulted him by means of the door. On August 24 appellants were inmates at M.C.I. at Walpole serving sentences for other crimes, and were assigned to cells in block ten. The state trooper had exhibited to Reilly an array of photographs at the interview when he made the identification. The state trooper prepared a written report after interviewing Reilly and