Professor Robinson said if the Labour leadership had stood down Mr Hughes immediately after learning of the police investigation, he could have made an immediate comeback after being cleared.
Instead the party leadership kept it quiet for almost three weeks, sending Mr Hughes on leave only after the allegations became public. The next day Mr Hughes was stood down from his portfolios, and a day later he had resigned.
"[But] it didn't really change the amount of disrespect people already had for [party leader] Phil Goff. It didn't really go up or down because it was already so low," Professor Robinson said.