  Some puzzling aspects of higher spin field theory in Minkowski space-time,
such as the tracelessness constraints and the search for an underlying physical
principle, are discussed. A connecting idea might be provided by the recently
much researched continuous spin representations of the Poincar\'e group. The
Wigner equations, treated as first class constraints, yields to a
four-constraint BRST formulation. The resulting field theory, generalizing free
higher spin field theory, is one among a set of higher spin theories that can
be related to previous work on unconstrained formulations. In particular, it is
conjectured that the unconstrained higher spin theory of Francia and Sagnotti
is a limit of a continuous spin theory. Furthermore, a simple analysis of the
constraint structure reveals a hint of a physical rationale behind the trace
constraints.
