dissenting.
We have here a Fourth Amendment question concerning the validity of an arrest. If the police see a crime being committed they can of course seize the culprit. If a person is fleeing the scene of a crime, the police can stop him. And there are the cases of “hot pursuit” and other instances of probable cause when the police can' make an arrest. But normally an arrest should be made only on a warrant issued by a- magistrate on a showing of “probable cause, supported by oath or affirmation,” as required by the Fourth Amendment. At least since Mapp v. Ohio, 367 U. S. 643, the States are as much bound by those provisions as is the Federal Government. But for the Fourth Amendment they could fashion the rule for arrests that "the Court now approves. With all deference, the requirements of the Fourth Amendment now make that conclusion unconstitutional.
No warrant for the arrest of petitioner was obtained in this case. The police; instead of going to a magistrate *315and making a showing of “probable cause” based on their informant’s tip-off, acted on their own. They, rather than the magistrate, became the arbiters of “probable cause.” The Court’s approval of that process effectively rewrites the Fourth Amendment.
In Roviaro v. United States, 353 U. S. 53, 61, we held that where a search without a warrant is made on the basis of communications of an informer and the. Government claims the police had “probable cause,” disclosure of the identity of the informant is normally required. In no other way can the defense show an absence of “probable .cause.” By reason of Mapp v. Ohio, supra, that rule is now applicable to the States.
In Beck v. Ohio, 379 U. S. 89, 96, we said:
“An arrest without a warrant bypasses the safeguards provided by an objective predetermination of probable cause, and substitutes instead the far less reliable procedure of an after-the-event justification 'for the arrest or search, too likely to be subtly influenced by the familiar shortcomings of hindsight judgment.”
For that reason we have weighted arrests with wárrants more heavily than arrests without warrants. See United States v. Ventresca, 380 U. S. 102, 106. Only 'through the informer’s testimony .can anyone other than the arresting officers determine “the persuasiveness of the facts relied on . . .' to show probable cause.” Aguilar v. Texas, 378 U. S. 108, 113.1 Without that disclosure neither we nor the lower courts can ever know whether there was “probable cause” for the arrest. Under the present decision we leave the Fourth Amendment exclusively in the custody of the police. As stated by Mr. Justice Schaefer dissenting in People v. Durr, 28 Ill. 2d 308, 318, 192 N. E. 2d 379, 384, unless the identity of the informer is disclosed “the policeman himself eon-*316clusively determines the validity of his own arrest.” That was the view of the Supreme Court of California in Priestly v. Superior Court, 50 Cal. 2d 812, 818, 330 P. 2d 39, 43:
“Only by requiring disclosure and giving the defendant an opportunity to present contrary or impeaching evidence as to the truth of the officer’s testimony and the reasonableness of his reliance on the informer can the court make a fair determination of the issue. Such a requirement does riot unreason- . ably discourage the free flow of information to law enforcement officers or otherwise impede law enforcement. Actually its effect is to compel independent investigations to verify information given by an informer or to uncover other facts that establish reasonable cause to make an arrest or search.”
There is no way to determine the reliability of Old Reliable, the informer, unless he is produced at the trial and cross-examined. Unless he is produced, the Fourth Amendment is entrusted to the tender mercies of the police.2 What we do today is to encourage arrests and searches without warrants. The whole momentum of criminal law administration should be in precisely the opposite direction, if the Fourth Amendment, is to remain a vital force. Except in rare and emergency cases, it requires magistrates to make the findings of “probable cause.”' We should be mindful of its command that a judicial mind should be interposed between the police and the citizen. We should also be mindful that “disclosure, rather than suppression, of relevant materials ordinarily promotes the proper administration of criminal justice.” Dennis v. United States, 384 U. S. 855, 870.
Quoting from Giordenello v. United States, 357 U. S. 480, 486.
It is not unknown for the arresting officer to misrepresent his connection, with the informer, his knowledge of the informer’s reliability, or the information allegedly obtained from the informer. See, e. g., United States v. Pearce, 275 F. 2d 318, 322.