  In this paper we examine the saturation conjecture on decompositions of
tensor products of irreducible representations for complex semisimple algebraic
groups of type $D$ (the even \emph{spin} groups: Spin$(2n)$ for $n\ge 4$ an
integer), extending work done by Kumar-Kapovich-Millson on Spin(8). Our main
theorem asserts that the saturation conjecture holds for Spin(10) and Spin(12):
for all triples of dominants weights $\lambda,\mu,\nu$ such that
$\lambda+\mu+\nu$ is in the root lattice, and for any $N>0$, $$
\left(V(\lambda)\otimes V(\mu)\otimes V(\nu)\right)^G \ne 0 $$ if and only if
$$ \left(V(N\lambda)\otimes V(N\mu)\otimes V(N\nu)\right)^G\ne 0, $$ for $G=$
Spin(10) or Spin(12). Some related results for groups of other types are listed
as well.
