“ Yet, after Harris, there is no longer any real incentive for police to obey Miranda. Credibility is always an issue when an accused takes the stand in his own defense. The license granted by the Harris majority to use Miranda-violative statements for impeachment purposes, therefore, foreshadows the possible use of tainted statements in almost every case. This opens the door to a calculated risk by police interrogators. If, in response to Miranda warnings, an accused indicates he wishes to have an attorney present during questioning, the request may be ignored with virtual impunity. ”

“ The accused may take cold comfort in the fact that if he does take the stand, the tainted statements may only be used for 'impeachment.' We have often noted the impossible task that faces a jury instructed to close its eyes to the fact that evidence introduced for a limited purpose is highly damaging on the ultimate issue of guilt, as well. ”

“ There is widespread agreement that police interrogation procedures are sensitive to the mandates of the courts:
' [T] he predominant incentive for interrogation is to obtain evidence for use in court. Consequently, police conduct in this area is likely to be responsive to judicial rules governing the admissibility of that evidence. 'There can be no doubt,' the President's Crime Commission reported, that the Supreme Court's rulings about interrogation procedures 'had much to do with the fact that today the third degree is almost non-existent. ”