  Triggered by a recent paper by Thomas, Hicks and Hosaka, we investigate which
observables can be used to determine the parity of the $\Theta^+$ from the
reaction $\vec p\vec p \to \Sigma^+\Theta^+$ near its production threshold. In
particular, we show that the sign of the spin correlation coefficient $A_{xx}$
for small excess energies yields the negative of the parity of the $\Theta^+$.
The argument relies solely on the Pauli principle and parity conservation and
is therefore model--independent.
