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.