Was his driver's license administratively suspended? If it was, he is probably within a timeframe to appeal the suspension and he needs to get an attorney ASAP to appeal. As soon as the suspension is final, he must report the suspension to FAA medical (I believe within 60 days). First suspension for failure of alcohol testing or refusal to submit to alcohol testing, or for first DWI offense conviction is no big deal. Failure to report IS A BIG DEAL. I don't know if conviction for DWAI is an offense that must be reported. I doubt it, but I don't know. I live in Texas, and there is no such offense.
If he is not suspended administratively, or convicted of a criminal offense then there is no requirement to report anything to the FAA.
email me @robertdburns@sbcglobal.net if any more Q's.