concurring.
I adhere to the view that the admission at trial of evidence acquired in alleged violation of Fourth Amend*55ment standards is not of itself sufficient ground for a collateral attack upon an otherwise valid criminal conviction, state or federal. See Harris v. Nelson, 394 U. S. 286, 307 (dissenting opinion); Kaufman v. United States, 394 U. S. 217, 242 (dissenting opinion). But until the Court adopts that view, I regard myself as obligated to consider the merits of the Fourth and Fourteenth Amendment claims in a case of this kind. Upon that premise I join the opinion and judgment of the Court.