If Cohen pleads guilty to bank fraud related to his taxi medallion business, that doesn't implicate Trump.
But if Cohen pleads guilty in connection with campaign finance case, that could directly implicate Trump /1
If Cohen conspired with Trump to make payments to Stormy Daniels in order to help the campaign, then they both could potentially be liable for Cohen making unreported, excessive in-kind contributions to the campaign (and perhaps other charges) /2
As I explained most recently in this @Slate piece, the question turns on motive, and it appears that prosecutors recently found good evidence of Cohen's motive which could subject him to criminal liability /3
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