Ghomeshi hired her because of the reputation she already had from other cases, whether successes or valiant failures . As for the witnesses, Henein had to gather the evidence, question it,  see the connections,  put it together,  draw plausible conclusions, anticipate problems, and then get the witnesses to do themselves in on the stand. It's not as though the last happens all by itself.  It's worth noting that neither the male prosecutor nor the male attorneys for the witnesses (one of whom writes for the G and M regularly) seem to have been very good at this,  and were, as a result, caught quite flatfooted at the trial.