My 18 year old child was issued a non traffic citation for underage drinking by campus police.

There are a lot of reasons to plead not guilty to an underaged drinking citation.  The first is that it carries with it a license suspsnsion and high fines.  It is also an escalating defense, so each offense gets more serious.  Pleading not guilty gives you a chance to explore diversionary programs which most counties offer for this offense.  In general if you have the time a not guilty plea can lead to a better outcome.  Attorneys fees in these types of cases are usually surprisingly reasonable.  Its worth your time to at least talk to local counsel to see how they can help.  You may be surprised at how small the fee is compared to how much positive impact they can bring to his case.