The response to your question depends on what state the offense took place. In Massachusetts, your son may have actually have already helped his defense significantly by refusing the test, despite the fact that he has likely incurred an initial license loss for refusing the test. Massachusetts law provides for progressive penalties fror fo refusing the breath test from 180 days to lifetime, depending on prior convictions. This suspension must be appealed within 15 days, initially to the RMV, and subsequently to the court with jurisdiction over the case- in- chief .
I strongly encourage you to contact one of the many experienced attorneys linked to this site, specifically one from your home state to have the matter evaluated immediately.
In the event this is a Massachusetts matter, I can be reached at gelanelaw@yahoo.com or by the web www.gelanelaw.com