Your son should IMMEDIATELY talk to a competent DUI lawyer. He has only ten days to demand a hearing on his license suspension. If he doesn't get the demand in to the Department of Motor Vehicles within that time, he will lose his license for one year, with the first 90 days of the suspension being absolute hard time with no driving whatsoever. After that, from day 91 to day 365, he may be eligible for a Business Purpose Only license, which will allow him to drive for purposes of maintaining his livelihood.
Don't fool yourself that they cannot prove a DUI without a breath test. If your son truly wasn't drinking, they may proceed against him on a DUI Drugs. Even the smell of a beer on a person's breath is enough for the State to get the case to a jury, so you really ought to consult somebody who knows what he or she is doing in DUI cases. Preferably, you should find a lawyer who has taken (or teaches) the NHTSA DUI and Field Sobriety Test Class, and someone who knows the protocols for being a Drug Recognition Evaluator.
You didn't say whether your son has ever had a DUI before. If he has, then it is even more crucial that he contact a lawyer ASAP so that important evidence is not lost. The best DUI lawyers will immediately go out to the scene and take pictures, so that you can catch them if the police try to make things up later. Good luck.
When interviewing a DUI defense lawyer ask the following questions:
What percentage of your annual caseload is relegated to defending DUI?
How many DUI jury trials did you have in the past 12 months?
Can you provide a list of DUI training seminars or conferences attended in the past 2 to 5 years?
What percentage of your clients enter a plea of guilty to the crime charged?
Have you or any members of your firm written articles or books related to defending DUIs?
How many lawyers are in the firm, and are they all DUI defense attorneys? If so, will they collaborate with their colleagues about your DUI case?
How many years have you defended DUI cases?
I agree with the other answers posted. I would add that you should check the website for the National College of DUI Defense to find a qualified DUI attorney in your area.
Sign up to receive a 3-part series of useful information and legal advice about DUIs.