The issue in criminal prosecutions is the need to prove guilt beyond reasonable doubt.  This is a very hight standard; much higher than the standard of "a balance pf probabilities" in a civil law suit.  The rationale for this is that, in a democracy, we do not want the state - with its immense resources - to lock away people unless guilt can be very clearly established.  In the Halifax case, the circumstantial evidence  would have likely been enough to prove civiil liability on a balance pf probabilities.  But I can see how a judge in a criminal case might not find guilt proven beyond all reasonable  doubt where the female cannot recall enough of what happened to confirm that she did not give consent.

Instead, why not establish a fund in sexual assault cases of this type (as the Charter Fund ) to pay the legal fees of women who wish to sue in such cases?  They could  recover punitive and other damages, and some lesser degree of justice and vindication,  with a lower burden of proof.