  It is shown that the transferring of light signal faster-than-c can take
place exclusively as the instantaneous quantum tunneling. Its extent (space
size of instanton) must be inversely relative to lack of energy till nearest
stable or resonant state. ''Superluminality'' leads to nonlocality ''in
small'', in a near field zone, and can be described by 4-vector $A_{\mu}$, the
$\mathbf{E}$ and $\mathbf{H}$ fields remain local.
  These assertions are proven, independently, in the frameworks of general
field theory and by the theory of time duration of scattering, with taking into
account the entropy growing. They are correlated with peculiarities of
tunneling and frustrated total reflection. The results correspond to the Wigner
formulation of causality: ''The scattered wave cannot escape a scatterer before
the initial wave reaches it'' and are conformed to experimental data on
superluminal transferring.
