Among other things, you check to see if the same person is registered in multiple places, states, under similar names, if they have been voting while in prison, while dead, after moving to another address/jurisdiction/states, etc. Problems with any of this could show systemic corruption of the registration process and voter rolls.
You can also compare the number of votes cast by precinct with the number of legally registered, active voters.
I have to presume that JD will continue to pursue all this cross checking, as so far no other org/institution seems to be taking this on.
So it was a civil court battle to obtain the voter lists and now it will be another court battle to demand those lists be purged of deadwood, after they are examined to find the dead voters or match to names in other counties....
I get exhausted thinking about all the work that JD has to do to guarantee what our government should already be doing...ensuring that our elections are not full of fraud.