"Curtilage" describes the immediate physical space surrounding a house. The house and curtilage are historically characterized as core areas protected by the Fourth Amendment from warrantless searches. Numerous court decisions address what constitutes an improper curtilage search. A July 11, 2013, decision by the U.S. Court of Appeals for the Eighth Circuit, U.S. v. Bausby, involved events resulting from a citizen's suspicion that a motorcycle in the defendant's chain-link fenced front yard with a "for sale" sign that contained a telephone number was stolen. In brief summary, police entered the yard and subsequently obtained a search warrant for the house. While conducting the search the police found a firearm and the defendant was convicted of being a felon in possession of a firearm. Part of the appeal addressed the lawfulness of the initial entry in the yard.
Two Eighth Circuit judges decided that the yard was not curtilage because the open display of the motorcycle with the "for sale" sign invited the public to enter the yard and knock on the front door. One judge believed the yard was curtilage due to the location, fence, telephone number, and a "Beware of Dog" sign on the fence. Nevertheless, all three judges decided that the police could enter the yard to knock on the front door and inquire about the motorcycle.
In March 2013, the U.S. Supreme Court decided in a 5:4 decision, Florida v. Jardines, that the warrantless use of a drug-sniffing dog at the front door of an apparently unfenced house was an unlawful entry and search of curtilage. While individuals might lawfully knock on the front door, using the dog was not proper. The dissent emphasized the right to knock and the lack of any prior decisions prohibiting an accompanying dog.
Drones and related technology complicate curtilage questions and are beyond the scope of this comment. Regarding physical entries by police, the apparent trend, illustrated by the Eighth Circuit, is to allow "plain view," "knock and talk," "good faith," and "implied invitee entry" warrantless curtilage entries. To create a "reasonable expectation of privacy" many decisions require some combination of solid physical barriers, locked gates, covers, security systems, no open sidewalks or driveways, and "no trespassing" signs. Additionally the mailbox, utility meters, and trash collection locations must be outside of this protected area to preclude any implied right to enter. Significant curtilage protections of these types are often impossible to create.
We may anticipate increasing curtilage legal issues. Curtilage protections impact the sanctity of one's house and the right to privacy, both of which are fundamental in a free society.