This article analyses proportionality as a potential element of a theory of
morally justified surveillance, and sets out a teleological account. It draws on
conceptions in criminal justice ethics and just war theory, defines teleological
proportionality in the context of surveillance, and sketches some of the central
values likely to go into the consideration. It then explores some of the ways in
which deontologists might want to modify the account and illustrates the
difficulties of doing so. Having set out the account, however, it considers whether
the proportionality condition is necessary to a theory of morally justified
surveillance. The article concludes that we need and should apply only a necessity
condition, but notes that proportionality considerations may retain some use in in
practice, as a form of coarse‐grained filter applied before assessing necessity when
deliberating the permissibility of potential forms of surveillance
