  A boson of spin-j>1 can be described in one of the possibilities within the
Bargmann-Wigner framework by means of one sole differential equation of order
twice the spin, which however is known to be inconsistent as it allows for
non-local, ghost and acausally propagating solutions, all problems which are
difficult to tackle. The other possibility is provided by the Fierz-Pauli
framework which is based on the more comfortable to deal with second order
Klein-Gordon equation, but it needs to be supplemented by an auxiliary
condition. Although the latter formalism avoids some of the pathologies of the
high-order equations, it still remains plagued by some inconsistencies such as
the acausal propagation of the wave fronts of the (classical) solutions within
an electromagnetic environment. We here suggest a method alternative to the
above two that combines their advantages while avoiding the related
difficulties. Namely, we suggest one sole strictly (j,0)+ (0,j) representation
specific second order differential equation, which is derivable from a
Lagrangian and whose solutions do not violate causality. The equation under
discussion presents itself as the product of the Klein-Gordon operator with a
momentum independent projector on Lorentz irreducible representation spaces
constructed from one of the Casimir invariants of the spin-Lorentz group. The
basis used is that of general tensor-spinors of rank-2j.
