  We study the joint probability distribution of normal and tangential
frictional forces in jammed granular media, $P_{\mu}(f_t, f_n)$, for various
friction coefficient $\mu$, especially when $\mu = \infty$. A universal scaling
law is found to collapse the data for $\mu=0$ to $\infty$ demonstrating a link
between force distribution $P_{\mu}(f_t, f_n)$ and average coordination number,
$z^{\mu}_c$. The results determine $z_c^\mu$ for a finite friction coefficient,
extending the constraints counting argument of isostatic granular packing to
finite frictional packings.
