Usually the power to require another driver to produce their cell phone records only exists after a lawsuit or legal proceeding has been filed in court. If you absolutely need the other driver’s cell phone records or electronic data right away, filing suit immediately after the wreck may be your best option.  Another “best practice,” is to send a request to the at-fault driver or their representative or insurance company demanding that the phone and records be preserved in the event of future litigation.  A party’s failure to preserve evidence when a claim or possible lawsuit is known about can, in some cases, result in civil penalties.