The first thing to notice about the Democrats’ choice of evidence is what is not included. If news reports are correct, the firing of FBI director James Comey, once treated in media discussions as Exhibit A in the case for obstruction, is not among the episodes Democrats will highlight. Nor are the conversations between Trump and Comey that Comey wrote up in his famous memos, including a talk in which Trump allegedly asked Comey to go easy on Michael Flynn — another episode that was routinely discussed in the media as solid evidence of obstruction. Nor are the president’s efforts to spin the public story of the June 9, 2016 Trump Tower meeting — yet another incident often characterized as obstruction.

Also important to remember is that the Muller investigation was not actually obstructed by the president, and neither was the FBI Trump-Russia investigation that preceded it. In the report, Mueller often argued that this or that act — say, firing Mueller — could have obstructed the investigation, had it actually occurred. But it did not. So the Democrats’ accusations of obstruction will in fact be accusations of attempted obstruction.

Finally, it is important to recall that Mueller could never establish that the underlying crime he was assigned to investigate — conspiracy or coordination between the Trump campaign and Russia — actually took place. So in Wednesday’s hearing, Democrats will be showcase an investigation that was not obstructed into a crime that investigators could not establish actually happened.