FOOTNOTES

Footnote 1

Possession of these items, if unregistered, would violate 18 U. S. C. §922(o)(1) and 26 U. S. C. §5861.

Footnote 2

The warrant stated: "[T]here is now concealed [on the specified premises] a certain person or property, namely [a] single dwelling residence two story in height which is blue in color and has two additions attached to the east. The front entrance to the residence faces in a southerly direction." App. to Pet. for Cert. 26a.

Footnote 3

The affidavit was sealed. Its sufficiency is not disputed.

Footnote 4

For this reason petitioner's argument that any constitutional error was committed by the Magistrate, not petitioner, is misplaced. In Massachusetts v. Sheppard, 468 U. S. 981 (1984), we suggested that "the judge, not the police officers," may have committed "[a]n error of constitutional dimension," id., at 990, because the judge had assured the officers requesting the warrant that he would take the steps necessary to conform the warrant to constitutional requirements, id., at 986. Thus, "it was not unreasonable for the police in [that] case to rely on the judge's assurances that the warrant authorized the search they had requested." Id., at 990, n. 6. In this case, by contrast, petitioner did not alert the Magistrate to the defect in the warrant that petitioner had drafted, and we therefore cannot know whether the Magistrate was aware of the scope of the search he was authorizing. Nor would it have been reasonable for petitioner to rely on a warrant that was so patently defective, even if the Magistrate was aware of the deficiency. See United States v. Leon, 468 U. S. 897, 915, 922, n. 23 (1984).

Footnote 5

It is true, as petitioner points out, that neither the Fourth Amendment nor Rule 41 of the Federal Rules of Criminal Procedure requires the executing officer to serve the warrant on the owner before commencing the search. Rule 41(f)(3) provides that "[t]he officer executing the warrant must: (A) give a copy of the warrant and a receipt for the property taken to the person from whom, or from whose premises, the property was taken; or (B) leave a copy of the warrant and receipt at the place where the officer took the property." Quite obviously, in some circumstances--a surreptitious search by means of a wiretap, for example, or the search of empty or abandoned premises--it will be impracticable or imprudent for the officers to show the warrant in advance. See Katz v. United States, 389 U. S. 347, 355, n. 16 (1967); Ker v. California, 374 U. S. 23, 37-41 (1963). Whether it would be unreasonable to refuse a request to furnish the warrant at the outset of the search when, as in this case, an occupant of the premises is present and poses no threat to the officers' safe and effective performance of their mission, is a question that this case does not present.

Footnote 6

The Court of Appeals' decision is consistent with this principle. Petitioner mischaracterizes the court's decision when he contends that it imposed a novel proofreading requirement on officers executing warrants. The court held that officers leading a search team must "mak[e] sure that they have a proper warrant that in fact authorizes the search and seizure they are about to conduct." 298 F. 3d 1022, 1027 (CA9 2002). That is not a duty to proofread; it is, rather, a duty to ensure that the warrant conforms to constitutional requirements.

Footnote 7

We do not suggest that an official is deprived of qualified immunity whenever he violates an internal guideline. We refer to the ATF Order only to underscore that petitioner should have known that he should not execute a patently defective warrant.

Footnote 8

Although both Sheppard and Leon involved the application of the "good faith" exception to the Fourth Amendment's general exclusionary rule, we have explained that "the same standard of objective reasonableness that we applied in the context of a suppression hearing in Leon defines the qualified immunity accorded an officer." Malley v. Briggs, 475 U. S. 335, 344 (1986) (citation omitted).

Footnote 9

Justice Kennedy argues in dissent that we have not allowed " 'ample room for mistaken judgments,' " post, at 6 (quoting Malley, 475 U. S., at 343), because "difficult and important tasks demand the officer's full attention in the heat of an ongoing and often dangerous criminal investigation," post, at 3. In this case, however, petitioner does not contend that any sort of exigency existed when he drafted the affidavit, the warrant application, and the warrant, or when he conducted the search. This is not the situation, therefore, in which we have recognized that "officers in the dangerous and difficult process of making arrests and executing search warrants" require "some latitude." Maryland v. Garrison, 480 U. S. 79, 87 (1987).

Nor are we according "the correctness of paper forms" a higher status than "substantive rights." Post, at 6. As we have explained, the Fourth Amendment's particularity requirement assures the subject of the search that a magistrate has duly authorized the officer to conduct a search of limited scope. This substantive right is not protected when the officer fails to take the time to glance at the authorizing document and detect a glaring defect that Justice Kennedy agrees is of constitutional magnitude, post, at 1.