In a letter to Attorney General William Barr, White House Counsel Emmet Flood blasted Special Counsel Robert Mueller’s report about his probe into Russian collusion and potential obstruction of justice committed by President Donald Trump—calling it “part ‘truth commission’ report and part law school exam paper.”

Flood claimed the report “suffers from an extraordinary legal defect,” failing to “comply with the requirements of governing law.” The White House lawyer took issue with Mueller’s conclusion that the evidence his team gathered did not “exonerate” the president.

“Prosecutors simply are not in the business of establishing innocence, any more than they are in the business of ‘exonerating’ investigated persons,” he wrote. “Because they do not belong to our criminal justice vocabulary, the SCO’s inverted-proof-standard and ‘exoneration’ statement can be understood only as political statements.”

By making political statements, Flood said Mueller and his team “failed in their duty to act as prosecutors and only as prosecutors.” He accused the special counsel’s team of not acting independently and insisted the report was “laden with factual information that has never been subjected to adversarial testing or independent analysis.”

Flood also addressed speculation that the report was intended to be a “road map” for Congress to start impeachment hearings. If that was true, he wrote to Barr that it was further evidence of Mueller’s “refusal to follow applicable law.”

Mueller did not find that Trump or anyone on his campaign colluded with Russians to interfere in the 2016 election, though the report did state that Russians were successful in interfering in a “sweeping and systematic fashion.” However, the report asserted that Mueller’s team was not able to “conclusively” determine whether or not Trump obstructed justice—adding that the evidence they gathered does “not conclude that the President committed a crime [but] does not exonerate him.”

Upon receiving the report from Mueller, Barr came to his own conclusions about the obstruction of justice issue alongside outgoing Deputy Attorney General Rod Rosenstein—with both of them concluding that the 10 instances of potential obstruction outlined in the report were not enough to bring charges against the president.

Barr’s conclusions about the report were subject to intense scrutiny when he testified before the Senate Judiciary Committee Wednesday, with Sen. Kamala Harris (D-CA) questioning whether or not Barr took a look at the underlying evidence of the report before making the charging decision.

Other senators also took aim at Barr’s decision to release his own “summaries” of the report rather than releasing Mueller’s own executive summaries, calling his decision an attempt at spinning the report before its full release to the public.