have a paper trail

To have physical or digital documentation of a person's or group's activity. It's in your best interest to have a paper trail throughout these negotiations. That way, you can show exactly what was agreed upon, should the other party try to renege on their commitments. Frank swore that he wasn't using the company's computer for illegal activities, but the CEO had a paper trail that proved otherwise. Of course they paid you in cold, hard cash—these con artists don't want to have a paper trail!