What is Justice Harlan's formulation of the privacy test?
I assume that you are asking about Justice Harlan’s formulation of the privacy test in his concurring opinion in the case of Katz v. United States. This was a case about the legality of a wiretap on a telephone booth. It was decided in 1967.
Harlan’s test has two prongs. Both of these are subjective. Taken together, they help us to determine when a search warrant is needed because a person is in a place that is private. The first prong of Harlan’s test has to do with the state of mind of the person whose actions are being observed. In order to have privacy, the person must act in a way that shows that they expect privacy. The second prong has to do with societal attitudes. The person must be in a place where society in general would typically think that the person should have privacy. It is not enough for the person to think they have privacy. The situation must also be one in which most people (not just the person in question) would expect to have privacy.
Thus, Harlan’s test in Katz is formulated with reference to the belief of the person whose actions are being observed and the beliefs of society as a whole.