John Paul Stevens

“ II The Court has developed a relatively straightforward test for determining what expectations of privacy are protected by the Fourth Amendment with respect to the possession of personal property. If personal property is in the plain view of the public, the possession of the property is in no sense "private" and hence is unprotected: "What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection." ”

“ The Court seems to acknowledge as much, since it indicates that the location of property can be private even when not in a home. See ante, at 720, n. 6. And even if it is assumed that a beeper infringes privacy interests only with respect to the location of items concealed within a home, the "search" that the Court concludes began when the can containing the beeper went into Karo's home did not end when it left the home. When the agents monitored the beeper at a later point and learned that the can was no longer in the home, the invasion of the privacy of Karo's home continued ”

“ Surely such an invasion is an "interference" with possessory rights; the right to exclude, which attached as soon as the can respondents purchased was delivered, had been infringed. [2] That interference is also "meaningful"; the character of the property is profoundly different when infected with an electronic bug than when it is entirely germ free. ”