In the framework of perturbative quantum field theory (QFT) we propose
a new, universal (re)normalization condition (called 'master Ward
identity') which expresses the symmetries of the underlying classical
theory. It implies for example the field equations, energy-momentum,
charge- and ghost-number conservation, renormalized equal-time
commutation relations and BRST-symmetry.
It seems that the master Ward identity can nearly always be satisfied,
the only exceptions we know are the usual anomalies. We prove
the compatibility of the master Ward identity with the other
(re)normalization conditions of causal perturbation theory, and for
pure massive theories we show that the 'central solution' of Epstein
and Glaser fulfills the master Ward identity, if the UV-scaling
behavior of its individual terms is not relatively lowered.
Application of the master Ward identity to the BRST-current of
non-Abelian gauge theories generates an identity (called 'master
BRST-identity') which contains the information which is needed for a
local construction of the algebra of observables, i.e. the elimination
of the unphysical fields and the construction of physical states in
the presence of an adiabatically switched off interaction.
