In Maryland v. Buie (1990) 494 U.S. 325, the seminal case regarding a protective sweep, the defendant and another man, one of whom was wearing a red jogging suit, robbed a restaurant.
Officers obtained an arrest warrant for the defendant and executed it at the defendant's residence. Once inside, an officer shouted into the basement for everyone to come out.
Defendant did so and was arrested. Another officer entered the basement in case someone else was down there, and saw in plain sight a red jogging suit which he seized. (Buie, supra, 494 U.S. at p. 328.)
The Supreme Court upheld the seizure of the jogging suit, stating:
"We conclude that the Fourth Amendment would permit the protective sweep undertaken here if the searching officer 'possessed a reasonable belief based on "specific and articulable facts which, taken together with the rational inferences from those facts, reasonably warranted" the officer in believing,' , that the area swept harbored an individual posing a danger to the officer or others." (Id. at p. 327.)
In People v. Celis (2004) 33 Cal.4th 667, the court expanded the protective sweep authorized by Buie to include a detention made outside the suspect's home. "From the high court's decision in Buie, supra, 494 U.S. 325, we draw these conclusions: A protective sweep of a house for officer safety as described in Buie, does not require probable cause to believe there is someone posing a danger to the officers in the area to be swept. (Buie, supra, at p. 327.) . . . A protective sweep can be justified merely by a reasonable suspicion that the area to be swept harbors a dangerous person. (Buie, supra, at p. 327.)" (Celis, supra, 33 Cal.4th at p. 678, original italics.)
In People v. Celis, law enforcement officers, including Detective John Strain, were investigating a drug operation whose members were concealing and transporting drugs in large truck tires. Defendant came under suspicion and he and his residence were placed under surveillance. Defendant drove to a tire store where he obtained an air pressurizing tank. Later that day, he drove to the Mexican border, parked and walked across the border and the agents lost sight of him. The next day, accompanied by his wife, defendant drove around San Diego in an evasive manner. Later defendant returned to the same tire store where he obtained a deflated tire which was too big for his vehicle. Still that same day, defendant, accompanied by Luis Ordaz, returned to the tire store with an air pressurizing tank, remained a while, then returned to defendant's residence and took the tank inside. (People v. Celis, supra, 33 Cal.4th at pp. 671-672.)
About 40 minutes later, defendant emerged from his house rolling the previously deflated tire toward the alley. Ordaz drove into the alley in a pickup. Believing the tire contained either money or drugs, Detective Strain, along with other officers, detained defendant and Ordaz. Because Detective Strain was aware that defendant lived with his wife and "'possibly a male juvenile,'" Detective Strain and other officers entered defendant's home "to determine if there was anyone inside who might endanger their safety." No one was found, but inside a wooden box, large enough to conceal someone, they found packages of cocaine. (Celis, supra, 33 Cal.4th at pp. 672-673.)
Celis held these facts did not create a reasonable suspicion justifying the protective sweep. The court reasoned that because the agents had not kept track of who was in the house, they lacked knowledge that anyone else was in defendant's home. (Celis, supra, 33 Cal.4th at p. 679.)
Further, neither the defendant nor Ordaz was armed at the time of the detention and no weapons had been found during earlier investigations of the trafficking ring. (Id. at p. 672.)
Hence, under all of the circumstances, the agents had no grounds to reasonably suspect there were other persons present to threaten their safety. (Id. at pp. 679-680.)