What is the effect of direct communication between a defendant and his lawyer?

'Accepting the prosecutors' evidence as true, defendant's participation in the crime had already been established and, therefore, no further investigation was necessary. . . . If the evidence of guilt is as strong as the prosecutor contends, such direct communication [with the defendant in the absence of counsel] is all the more offensive because it was unnecessary. If there is doubt about defendant's guilt, it should not be overcome by a procedure such as this.' United States v. Springer, 460 F.2d 1344, 1354 (7th Cir. 1972) (dissenting opinion).