The U.N. human rights experts said the pardons violated U.S. obligations under international law. The question from an American point of view is "are the pardons of employees of the private security firm Blackwater owned by Trump's education secretary Betsy DeVos' brother legal". And if they are, the pardons will stand, if not I suppose they will be rounded up and put back into prison. 

Though I find these pardons rather strange and questionable, IMO these pardons are part of the legal pardon process under Article Two, Section 2, Clause 1 of the U.S. Constitution,