  Lorentz Invariance Violation introduced as a generic modification to particle
dispersion relations is used to study high energy cosmic ray attenuation
processes. It is shown to reproduce the same physical effects for vacuum
Cherenkov radiation, as in some particular models with spontaneous breaking of
Lorentz symmetry. This approximation is also implemented for the study of
photon decay in vacuum, where stringent limits to the violation scale are
derived from the direct observation of very high energy cosmic ray photon
events on gamma telescopes. Photo production processes by cosmic ray primaries
on photon background are also addressed, to show that Lorentz violation may
turn off this attenuation process at energies above a well defined secondary
threshold.
