At one point TPC symmetry or time-parity-charge -symmetry was considered to be one of the most fundamental laws of physics. The basic idea is that any elementary event can happen forwards or backwards (symmetrical in time), left- or righthandedly (symmetrical in parity) and with a negative or positive charge (symmetrical in charge). More recently (late last century) a case was however found in which a certain particle will, as it decays, emit a smaller particle in a certain direction relating to the axis around which it is spinning. This, as far as I understand, is in violation with parity symmetry.