  Imagine an app on your phone or computer that can tell if you are being
dishonest, just by processing affective features of your facial expressions,
body movements, and voice. People could ask about your political preferences,
your sexual orientation, and immediately determine which of your responses are
honest and which are not. In this paper we argue why artificial
intelligence-based, non-invasive lie detection technologies are likely to
experience a rapid advancement in the coming years, and that it would be
irresponsible to wait any longer before discussing its implications. Legal and
popular perspectives are reviewed to evaluate the potential for these
technologies to cause societal harm. To understand the perspective of a
reasonable person, we conducted a survey of 129 individuals, and identified
consent and accuracy as the major factors in their decision-making process
regarding the use of these technologies. In our analysis, we distinguish two
types of lie detection technology, accurate truth metering and accurate thought
exposing. We generally find that truth metering is already largely within the
scope of existing US federal and state laws, albeit with some notable
exceptions. In contrast, we find that current regulation of thought exposing
technologies is ambiguous and inadequate to safeguard civil liberties. In order
to rectify these shortcomings, we introduce the legal concept of mental
trespass and use this concept as the basis for proposed regulation.
