Criminal Procedure

Reasonable Expectation of Privacy

Since Katz, a search is said to occur under the Fourth Amendment when the government violates a person's reasonable expectation of privacy. This comprises two parts:

  1. The person searched must have exhibited an actual subjective expectation of privacy.
  2. Society must be prepared to recognize that this expectation is objectively reasonable.
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.

Curtilage

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:

  1. The distance of the area from the home
  2. Whether the area is within an enclosure surrounding the home (I.e., if it's in a fence)
  3. The nature of the use to which the area is put
  4. 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.

Aerial Search

Aerial searches are not searches under the meaning of the Fourth Amendment to the Constitution of the United States as long as the police are in a lawful airspace because there is no reasonable expectation of privacy from being viewed from such places since anyone can fly a plane there.

Sense-Enhancing Technology

Sense-enhancing technology constitutes a search under the Fourth Amendment if the technology is not generally available to the public and it reveals information that one would reasonably expect to be private.

Thermal Imaging

According to Kyllo v. United States, taking a picture of the infrared light being emitted from someone's home is considered a search under the Fourth Amendment because it can reveal the heat being generated in various rooms of the house, which can reveal details about the interior of the home, which has the greatest expectation of privacy, and because when Kyllo v. United States was decided, infrared cameras were much more expensive than they are today.

Trash

Generally, there is no reasonable expectation of privacy in one's trash, and therefore a search of trash would not be a search under the meaning of the Fourth Amendment.

Factors such as the location of one's trash can show a reasonable expectation of privacy however.

Vehicles have lower expectations of privacy because they are made to transport one through the public and because they have windows allowing anyone to see inside.

There is no reasonable expectation of privacy in the phone numbers one dials, only in the contents of such calls.

Dog

Dogs can be used to search during a lawful traffic stop without it constituting a search under the Fourth Amendment to the Constitution of the United States because there is no reasonable expectation of privacy in the smells that one gives off.

A dog alerting during a search gives an officer probable cause.

Dogs being used within the curtilage of one's home is a search however because, even if though people generally have a license to enter premises for certain purposes like going up to the front door, bringing dogs to sniff is exceeding the police's license to enter and is therefore a trespass.