  We extend the use of Bell-inequalities to $\Phi \to K^0 \bar{K^0}$ decays by
exploiting analogies and differences to the well-known and experimentally
verified singlet-spin case. Contrasting with other analyses, our
Bell-inequalities are violated by quantum mechanics and can strictly be derived
from local realistic theories. In principle, quantum mechanics could then be
tested using unstable, oscillating states governed by a CP-violating
Hamiltonian.
