Minor Contributing to a Minor

My question involves criminal law for the state of: Ohio
While I was on vacation my 17 year old son had a few friends over and 2 girls, both 16, that came over decided they wanted to drink so they got into the fridge and drank some alcohol that my son's friend had someone buy them earlier in the week. My son and his friends didn't drink at all that night. Evidently 1 girl was on medication and got real sick so my son took her home. Her parents took her to the ER then called the cops on my son. The cops said that he was going to get charged for contributing to a minor. The girls didn't have permission from me to be at the house and both knew we were gone. What can I expect for my son and is there any thing I can do about the girls not having my permission to be there?

Until he is charged and the exact violation is noted, I can't say, but if will be charged with furnishing alcohol to minors or under this section, the penalty is a Misdemeanor of the 1st degree, punishable by a possible jail sentence of 6 months and a possible fine of $1,000.00

http://codes.ohio.gov/orc/4301.69

As far as civil liabilty, he is possibly liable if the parent's sue for the minors illness, etc. Ohio's Parental liability laws for the acts of minors is as follows, you can look them up as I copied and pasted from a site.

R.C. § 2307.70: Various
Conduct

R.C. § 3109.09: Property
Damage

R.C. § 3109.10: Personal Injury

R.C. § 4507.07: Auto Liability