The expectation of privacy test, originated from Katz v. United States is a key component of Fourth Amendment analysis. The Fourth Amendment protects people from warrantless searches of places or seizures of persons or objects, in which they have an subjective expectation of privacy that is deemed reasonable in public norms. The test determines whether an action by the government has violated an individual's reasonable expectation of privacy.
The Reasonable Expectation of Privacy Test
In Katz, Jutsice Harlan created the Reasonable Expectation of Privacy Test in his concurring opinion. Although it was not formulated by the majority, this test has been the main takeaway of the case. Justice Harlan created a two-part test:
- an individual has exhibited an actual (subjective) expectation of privacy
- the expectation is one that society is prepared to recognize as reasonable
If both of these requirements have been met, and the government has taken an action which violates this "expectation," then the government's action has violated the individual's Fourth Amendment rights.
Elaborating on & Applying the Test
According to the Supreme Court in Rakas v. Illinois (1978), the "expectation of privacy must have a source outside of the Fourth Amendment either by reference to concepts of real or personal property law or to understandings that are recognized and permitted by society."
For example, private homes are at the core of Fourth Amendment protection, as they are closely associated with the ownership interest in property law.
There are, however, exceptions to the Reasonable Expectation of Privacy Test. For example, federal Fourth Amendment protections do not extend to governmental intrusion and information collection conducted upon open fields; expectation of privacy in an open field is not considered reasonable. Some states, however, do grant protection to open fields.