UNITED STATES SUPREME COURT DECISIONS ON-LINE

Baltimore police officers obtained and executed a warrant to search the person of one McWebb and "the premises known as 2036 Park Avenue third floor apartment" for controlled substances and related paraphernalia. The police reasonably believed that there was only one apartment on the described premises, but in fact the third floor was divided into two apartment, one occupied by McWebb and one by respondent. Before the officers became aware that they were in respondent's apartment, they discovered the contraband that provided the basis for respondent's conviction for violating Maryland's Controlled Substances Act. The trial court denied respondent's motion to suppress the evidence, and the Maryland Court of Special Appeals affirmed. The Maryland Court of Appeals reversed and remanded for a new trial.

Held:

1. On the basis of the information that the officers disclosed, or had a duty to discover and to disclose, to the issuing Magistrate, the warrant, insofar as it authorized a search that turned out to be ambiguous in scope, was valid when it issued. The validity of the warrant must be judged in light of the information available to the officers at the time they obtained the warrant. The discovery of facts demonstrating that a valid warrant was unnecessarily broad does not retroactively invalidate the warrant. Pp. 480 U. S. 84-86.

2. The execution of the warrant did not violate respondent's rights under the Fourth Amendment. The validity of the search of his apartment pursuant to the warrant depends on whether the officers' failure to realize the overbreadth of the warrant was objectively understandable and reasonable, and it unquestionably was. The objective facts available to the officers at the time suggested no distinction between McWebb's apartment and the third-floor premises. Whether the premises described in the warrant are interpreted as the entire third floor or as McWebb's apartment, the officers' conduct was consistent with a reasonable effort to ascertain and identify the place intended to be searched within the meaning of the Fourth Amendment. Pp. 480 U. S. 86-89.

303 Md. 385, 494 A.2d 193, reversed and remanded.

STEVENS, J., delivered the opinion of the Court, in which REHNQUIST, C.J.,and WHITE, POWELL, O'CONNOR, and SCALIA, JJ., joined. BLACKMUN, clubjuris

Page 480 U. S. 80

J., filed a dissenting opinion, in which BRENNAN and MARSHALL, JJ., joined, post, p. 480 U. S. 89.