This is a case of technology outpacing statutes and regulations. This question came up last year and I ran it up the chain of command for formal action. Right now we're not too concerned about it if someone has their license on their smartphone. It's gotten to the point with these phones where you can board an airplane after being groped by TSA with just a ticket on a smartphone.

The statute is worded that you must carry the license as designated by the commissioner. I ran it up the chain again asking if the Commissioner can issue a ruling that an electronic version would be acceptable and that should cover it. I'll let you know how I make out.