This is the segment of Congressional testimony, that requires a team of Washington DC lawyers, to go through Comey's testimony, with a fine toothed political comb.

All of the disgruntled FBI personnel, under his reign (possibly terror), will be coming out of the woodwork, to refute Comey's statements.

If Comey is the only witness, without any witnesses or recording corroboration, then this testimony will be, "he said - he said", and it will come down to who gave the more convincing & believable story.