  Let $n \geq 10$ and let $f_a$ be the quadratic form
$f_a(x_1,\ldots,x_{2n})=\sum_{i=1}^{2n}x_i^2$. Assuming the Generalized Riemann
Hypothesis, we prove that every conjugacy class of $\mathrm{Spin}_{f_a}\left(
\mathbb{Z} \left[ \frac{1}{2} \right] \right)$ has finite width and describe
some consequences. To the best of our knowledge, this is the first time that
such a boundedness result is proved for an anisotropic higher rank arithmetic
group. In addition, we show that every higher rank arithmetic group in which
every conjugacy class has a finite width, with some natural upper bound on this
width, has the Congruence Subgroup Property. While the group
$\mathrm{Spin}_{f_a}(\mathbb{Z}[\frac{1}{2}])$ is known to have CSP, we hope
that the approach to CSP via conjugacy width will be fruitful.
  In a forthcoming paper, we will extend this result to many other anisotropic
spin groups.
