Furthermore:
The case of Katz v. U.S., 389 U.S. 347 (1967) considered a wiretap on a public telephone booth. The principal holding in this case was that the police had violated the defendant's privacy upon which he justifiably relied and the police made an unreasonable seizure under the Fourth Amendment to the U.S. Constitution. In Justice Harlan's concurring opinion in Katz, 389 U.S. at 361, a two-part test was proposed: (1) Did the person have an actual expectation of privacy in the communication? and (2) Does society recognize this expectation as reasonable? The U.S. Supreme Court accepted this two-part test in Smith v. Maryland, 442 U.S. 735, 740 (1979) and restated their acceptance again in California v. Ciraolo, 476 U.S. 207, 211 (1986). While Katz is a search and seizure case in criminal law, the reasonable expectation test has been applied in civil contexts.
You also didn't carry the argument to its conclusion.
In BENJAMIN PATEL, Petitioner v. STATE OF ARKLATEX;
The Court in previous holdings has indicated that an expectation of privacy exists when a guest stays overnight in the home of another. Minnesota v. Olsen, 495 U.S. 91 (1990). However, the Court is more reluctant to hold that a person with no previous connection to the premises, and who is briefly on the premises for business purposes, has an expectation of privacy. Minnesota v. Carter, 525 U.S. 83 (1998).
As for a guest's legal standing, the Supreme Court has deemed guests to have apparent authority to consent to the search of their hosts’ home, but has not recognized their right to have a reasonable expectation of privacy within that home.
Reading Gregory J. Wartman's THIS REASONABLE?: THE SUPREME COURT’S INCONSISTENTTREATMENT OF HOUSE GUESTS will be a very good first step in this discussion. It can be found here:
http://lawreview.law.pitt.edu/volumes/vol62i2/Wartman-%20387%20R.pdf#search='U.S.%20Supreme%20Court%20expectation%20of%20privacy%20in%20another's%20home'