Open Field Doctrine
The open field doctrine, as laid out in Oliver, states that searching an open field is not a search within the meaning of the Fourth Amendment because, even though it would be a trespass at common law, there is no reasonable expectation of privacy in an open field.
Land is not an open field if it is within the curtilage of the home.
The curtilage of a home is the land immediately surrounding it.
United States v. Dunn laid out four factors to determine where land is part of the curtilage or an open field:
- The distance of the area from the home
- Whether the area is within an enclosure surrounding the home (I.e., if it's in a fence)
- The nature of the use to which the area is put
- Steps taken to protect the area from observation
The basic analysis behind this is whether the land is so intimately tied to the home that it should be placed under the home's Fourth Amendment protection.