  Recently synthesized 3D materials with Dirac spectrum exhibit peculiar
electric transport qualitatively different from its 2D analogue, graphene.
Neglecting impuritiy scattering, the real part of the conductivity is strongly
frequency dependent (linear), while the imaginary part is non-zero (unlike in
undoped, clean graphene). The Coulomb interaction between electrons is
unscreened as in a dielectric and hence is long range. We demonstrate that the
interaction correction renders the electrodynamics nonlocal on a mesoscopic\
scale. The longitudinal conductivity $\sigma _{L}$ (related by charge
conservation to the electric susceptibility) and the transverse conductivity
$\sigma _{T}$ are different in the long wave length limit and consequently the
standard local Ohm's law description does not apply. This leads to several
remarkable effects in transport and optical response. We predict a charging
effect in DC transport that is a direct signature of the nonlocality. The
optical response of the WSM is also sensitive to the nonlocality. In these
materials p-polarized light generates bulk plasmons as well as the transversal
waves. The propagation inside the WSM is only slightly attenuated. At a
specific (material parameter dependent) frequency the two modes coincide, a
phenomenon impossible in a local medium. Remarkably, for any frequency there is
an incident angle where total absorption occurs, turning the WSM opaque.
