His entire investigation was based on two fragile pillars, which Mueller never questioned. If they collapse, Mueller is buried in the rubble. The first pillar is the FBI’s dubious “origin story.” The bureau states, and Mueller explicitly accepts, that its Trump investigation began in late-July 2016 after a low-level campaign volunteer, George Papadopoulos, spoke about Russia to an Australian diplomat in a London bar. Apparently, Papadopoulos also made exculpatory comments, which were not included (as legally required) in a subsequent search-warrant application.

But there is mounting evidence that Papadopoulos was not the first target and July 2016 was not the real starting date. Counter-intelligence investigations of Trump and his associates apparently began earlier and were never disclosed. Neither was widespread illegal spying on Americans by intelligence agencies and their private contractors. Still more surveillance was outsourced to friendly foreign intelligence agencies, which relayed their findings to Washington. Mueller never mentioned these problems — and possible crimes.

These omissions matter. They illustrate bias against Trump and suggest the report’s evidence may be tainted by omission and commission. They show Mueller’s extraordinary efforts to protect the law-enforcement institutions where he served for so many years. That protective shield is a problem because misconduct at DoJ and FBI is central to the inquiry.