In United States v. Johnson, No. 23-4255 (4th Cir. 2025), the U.S. Court of Appeals for the Fourth Circuit addressed a key Fourth Amendment issue: whether a warrantless dog sniff at the front door of an apartment, conducted in the hallway of a multi-unit building, constitutes an unlawful search.
The court held that it does not. This published decision affirms that trained narcotics-detection dogs may be used outside an apartment door—without a warrant or probable cause—so long as the hallway is a common area not subject to the exclusive control of the resident.
Case Background
Law enforcement suspected Eric Tyrell Johnson of trafficking fentanyl and heroin from Apartment 201 in a large Maryland apartment complex. Before obtaining a warrant, officers entered the building with management’s permission and conducted a “free air sniff” using a certified drug dog outside Johnson’s door. The dog alerted to narcotics, and officers subsequently obtained a warrant that led to the discovery of drugs, firearms, and cash.
Johnson moved to suppress the evidence, arguing that the warrantless dog sniff violated the Fourth Amendment in two distinct ways:
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Reasonable Expectation of Privacy: Johnson argued that the sniff functioned like a search because it used a specialized device (a trained dog) to reveal details of the home that would otherwise require physical intrusion—analogous to Kyllo v. United States, 533 U.S. 27 (2001).
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Physical Intrusion on Curtilage: He also contended that the area immediately outside his apartment door was part of the “curtilage” of his home, making the sniff a physical trespass similar to Florida v. Jardines, 569 U.S. 1 (2013).
The district court denied the motion, and the Fourth Circuit affirmed.
The Fourth Circuit’s Ruling
1. No Reasonable Expectation of Privacy in a Dog Sniff
The court rejected Johnson’s Kyllo-based argument, citing Illinois v. Caballes, 543 U.S. 405 (2005), and United States v. Place, 462 U.S. 696 (1983), which held that dog sniffs are sui generis—they reveal only the presence of contraband, in which there is no legitimate privacy interest. The Fourth Circuit emphasized that this doctrine applies regardless of whether the dog sniff is conducted on a suitcase, a vehicle, or a home’s exterior. Thus, the use of a trained K9 to detect narcotics odors at Johnson’s door did not violate any reasonable expectation of privacy.
2. No Trespass on Protected Curtilage
The court also held that the area in front of Johnson’s apartment door did not qualify as protected “curtilage” under the property-based approach endorsed in Jardines. Unlike the private front porch in Jardines, the hallway outside Johnson’s apartment was a common area used by other residents and cleaning staff, and building management routinely granted access to others. Importantly, Johnson had no legal right to exclude people from this hallway.
Applying the United States v. Dunn, 480 U.S. 294 (1987), factors for determining curtilage, the court found that although the hallway was proximate to the apartment, it was not enclosed with the unit, not under Johnson’s exclusive control, and not used for intimate domestic purposes. Therefore, it lacked Fourth Amendment protection.
Key Takeaways
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Dog sniffs do not constitute Fourth Amendment searches when they reveal only the presence of contraband, even outside a home.
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Common areas in apartment buildings, such as hallways, are generally not considered curtilage unless the resident has exclusive control or a right to exclude others.
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This decision aligns with the majority of federal courts that have upheld similar dog sniffs in apartment hallways.
Binding Case Law:
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Jurisdiction: United States Court of Appeals for the Fourth Circuit
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Binding in: Maryland, North Carolina, South Carolina, Virginia, West Virginia
Final Word
United States v. Johnson clarifies that the heightened privacy protections typically afforded to the home under the Fourth Amendment do not automatically extend to the shared hallways of apartment buildings. Unless a resident can demonstrate a property-based right to exclude others from the area outside their door, a warrantless K9 sniff in that space will not trigger constitutional scrutiny.