A few weeks ago I participated in a seminar on digital evidence, and one of the topics we discussed was cell phone records (subscriber information, call detail records, historical location data, etc.). That’s not surprising, since the widespread use of cell phones has made these records an increasingly common and important tool in criminal cases. Location data can help prove that the defendant was in the victim’s house at the time of the murder, call logs can help prove the co-conspirators were in regular contact with each other, and so on.
What did surprise me was when I asked a group of 75+ prosecutors how often they have used an affidavit to authenticate these kinds of records and get them admitted into evidence, without the need for live testimony by a witness from the company? Only one prosecutor had ever done so, and that was in a case with a pro se defendant. There seemed to be a lot of confusion about (i) whether this was even possible, (ii) old rules vs. new rules, and (iii) state court vs. federal court, so I thought this post would be a good opportunity to help clear things up.