In accepting an invitation to receive information about Hillary detrimental to her candidacy, Don Jr. committed no crime in meeting with Natalia Veselnikskaya who was there, for all we know, to provide information about the dealings of the Clinton Foundation perhaps in relation to human trafficking, what Team Trump little doubt was already looking into, and what at that point they wanted to keep under wraps. If what was brought to the attention of Team Trump in that meeting indicated criminal conduct by Hillary, the FBI could not be trusted as Comey who was boss then had demonstrated purposeful incompetence on behalf of Team Hillary by not recommending prosecution for her email charade.
