A 15 year old can certainly be named in a suit, along with his parents or guardians. Ultimately, the parents would be held financially liable for the infringing acts of their minor child in most cases.
If this involves a cease and desist letter, I would say that the first thing your child should do is to cease and desist from the allegedly infringing activity until you have consulted with a copyright attorney.
There are some defenses to claims of copyright infringement that may be available, and there might be some specific facts that can clear your 15 year old of the liability for any infringing activity, but the sooner you rectify this, the better. The financial consequences could be dire, depending upon the nature of the alleged infringement.
Either way, a quick consultation with a copyright attorney would be a safe bet.
This does not constitute legal advice or the engagement of my services as an attorney.
First, if this was criminal you would likely not have to ask. So I would not be very concerned about that unless your son was involved in a rather large illegal scheme.
Lots of people receive demand letters for CR infringement every day. Very few cases will go to litigation because it is almost never worth the effort and expense involved, but we don't have a crystal ball of course.
I suggest that you consult with a lawyer in private and discuss your options for responding in more detail. You can start by calling around to several for a free phone consultation, get some insights then pick the best fit to work with.
DISCLAIMER: this is not intended to be specific legal advice and should not be relied upon as such. No attorney-client relationship is formed with the law firm of Natoli-Lapin, LLC on the basis of this posting.
YES, a 15 year old can be sued and you, as parent, would also be named if you are the legal custodian of the 15 year old.
This is surely civil. It would not be a letter and you would have been talking with law enforcement if it was criminal, and would not need to ask.
My speculative guess is your 15 year old got an email from an ISP about illegal downloads with a copy of a demand letter from a film owner. If that is it, then any one of us here can handle it at a relatively nominal fee, as while the ISP keeps a log identifying who is assigned an IP address at any given time, the actual identity of your 15 year old is not known to CEG-TEK or whoever's accusatory letter is forwarded along with the ISP notice.
If, this is instead some notice regarding counterfeit eBay items or counterfeit Amazon items, or illegal Etsy stuff, then the copyright owner likely does have the identity information and this is more serious.
If this is about say, fake NFL merchandise, then it is even more serious as that can lead to criminal charges.
So, the first step for you is to pick one the attorneys and call for a consultation. The first 1/2 hr will usually be free if you ask for a free initial consultation. You should mention this Avvo question so the attorney knows you have released some public information, although you have done well in not revealing too much.
So, congratulations on realizing you need an attorney's help. Find the right one and this should all be solvable. In the meantime, do your best to reign in that 15 year old so the situation is not made worse.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.