Here's what happens if Mueller doesn't find anything on Trump -- and why both parties are unprepared: law professor

The possibility that special counsel Robert Mueller comes up empty-handed in his investigation of Donald Trump is a real one that neither Democrats nor Republicans appear to be prepared for, one law professor argued.

"Neither liberals nor conservatives have adequately considered this prospect," University of Arizona law professor Andrew Coan wrote in a CNN editorial Thursday.

Liberals, Coan noted, take it as "an article of faith" that the special counsel will come up with a "damning" report of Trump -- and although conservatives insist the president is innocent, "their incessant attacks on Mueller suggest a far more pessimistic outlook."

The professor noted that although there's ample reason to believe the investigation will provide bombshells -- including the public evidence that "suggests that Trump's campaign may indeed have sought to collude with the Russian government" -- the investigation could still end with a "whimper" rather than a "bang."

"Many of the possible crimes he is investigating turn on questions of intent that are legally murky and notoriously difficult to prove," Coan noted, adding later that "both sides could be wrong" with their premature conclusions.

If Mueller manages to complete the investigation unimpeded, regardless of the result, that would itself be a "miracle" and a testament to American institutions, the professor noted.

If he does not conclude that Trump colluded with Russia, Coan added, it won't "vindicate" the president.

"At most, it will establish that he is probably not a criminal -- at least so far as Russian election meddling is concerned," the professor wrote.

"It will not establish that the investigation was a witch hunt or even a waste of time," Coan concluded. "The whole point of an investigation is to find answers. Without Mueller's investigation, we would never know if the credible allegations against Trump and his associates were true."

Read the entire analysis via CNN.