State v. Brian Harold Duchow, 2008 WI 57, reversing unpublished decision
For Duchow: Melinda A. Swartz, SPD, Milwaukee Appellate
¶21 This second component reflects that protections from unreasonable searches and seizures, as described in the Fourth Amendment of the federal constitution  as well as Article I, § 11 of the state constitution,  must be determined by reference to the “‘scope of privacy that a free people legitimately may expect.'” State v. Whitrock, 161 Wis. 2d 960, 973, 468 N.W.2d 696 (1991) (quoting Rakas v. Illinois, 439 U.S. 128, 151 (1978)). “A reasonable expectation is one [that] is constitutionally ‘justifiable.'” Id. at 974 (citation omitted). No single factor is determinative in resolving whether one has a reasonable expectation of privacy; rather, we investigate the totality of the circumstances to resolve the question. Id. at 973-74.
¶22 Recognizing that the law requires an examination of the totality of the circumstances in determining whether an individual has a reasonable expectation of privacy, courts have identified a non-exclusive list of factors to discern whether an individual’s expectation of privacy in his or her oral statements is objectively reasonable. The factors include the following: (1) the volume of the statements; (2) the proximity of other individuals to the speaker, or the potential for others to overhear the speaker; (3) the potential for the communications to be reported;  (4) the actions taken by the speaker to ensure his or her privacy; (5) the need to employ technological enhancements for one to hear the speaker’s statements; and (6) the place or location where the statements are made.  See, e.g., Kee, 247 F.3d at 213-15.
Privacy interest in an oral statement is subject to a different calculus than where real property is ¶22 n. 18 (“We forgo applying the factors we most recently cited in State v. Bruski, 2007 WI 25, 299 Wis. 2d 177, 727 N.W.2d 503, for determining whether an individual’s expectation of privacy is reasonable. We do so because the Bruski factors apply to assertions of a privacy interest that were taken from the context of an expectation of privacy in real property. … While these factors may be instructive, we conclude that their focus on criteria relating to property renders them not directly applicable in evaluating whether an individual has an expectation of privacy in oral statements.”).