Expectation of privacy

In United States constitutional law the expectation of privacy is a legal test which is crucial in defining the scope of the applicability of the privacy protections of the Fourth Amendment to the United States Constitution. It is related to, but is not the same thing as a right of privacy, a much broader concept which is found in many legal systems (see privacy law).
There are two types of expectations of privacy:
A subjective expectation of privacy is an opinion of a person that a certain location or situation is private. These obviously vary greatly from person to person.
An objective, legitimate or reasonable expectation of privacy is an expectation of privacy generally recognized by society.
Examples of places where a person has a reasonable expectation of privacy are person's residence or hotel room and public places which have been specifically provided by businesses or the public sector to ensure privacy, such as public restrooms, private portions of jailhouses, or a phone booth.
In general, one cannot have a reasonable expectation of privacy in things held out to the public. A well-known example is that there is no privacy rights in garbage left for collection in a public place. Other examples include: account records held by the bank, a person's physical characteristics (including blood, hair, fingerprints, fingernails and the sound of your voice), what the naked eye can see below in public air space (without the use of special equipment), anything in open fields (eg. barn), odors emanating from your car or luggage and paint scrapings on the outside of your car.
While a person may have a subjective expectation of privacy in his/her car, it is not always an objective one, unlike a person's home.
The privacy laws of the United States include the notion of a person's "open fields"; that is, places where a person's possessions do not have an objective expectation of privacy.