In an audacious pre-Christmas round of pardons, President Trump granted clemency on Tuesday to two people convicted in the special counsel’s Russia inquiry, four Blackwater guards convicted in connection with the killing of Iraqi civilians and three corrupt former Republican members of Congress.

It was a remarkable assertion of pardon power by a president who has disputed his loss in the election and might be only the start of more to come in the final weeks before he leaves office on Jan. 20.

Mr. Trump nullified more of the legal consequences of an investigation into his 2016 campaign that he long labeled a hoax. He granted clemency to contractors whose actions in Iraq set off an international uproar and helped turn public opinion further against the war there. And he pardoned three members of his party who had become high-profile examples of public corruption.

Among those pardoned was George Papadopoulos, who was a foreign policy adviser to Mr. Trump’s 2016 campaign and who pleaded guilty in 2017 to making false statements to federal officials as part of the investigation by the special counsel, […]