I assume that this question is about the test that Justice Harlan proposed in his concurring opinion in Katz v. United States. I have therefore moved this question and reworded it. This was a two-pronged test that laid out rules for determining when a person had a right to privacy. This test was not accepted by the majority in this decision, but it was later accepted by the Court.
The first prong of Harlan’s test had to do with the person’s own expectations and behaviors. In order to have a right to privacy, the person must act as if they expect to be private. That is, they must do things like saying things that they would not want heard by anyone other than the person they were talking to. The second prong of the test had to do with how society as a whole would take the person’s expectation. That is, the expectation of privacy would have to seem reasonable to the average person.
Thus, Harlan’s test held that a person had the right to privacy (not to be overheard or otherwise searched) if they acted like they expected privacy and if their expectation was reasonable.