Can I be legally sued for a medical bill my 24 year old son incurred

You are liable for your adult son's finances only if the court has found that the son is an adult and is dependent on you. If you did not sign anything to obligate yourself to pay for your son's treatment, that likely is your defense. If there is a lawsuit, you need to respond to it; otherwise, you lose by default. You should review the specific facts with your attorney to find out your legal options.

Generally, no, an adult is not legally obligated to the debts of another adult, even if it is a child. However, if you signed anything, guaranteed anything, or your son is considered your dependent (due to disability, etc), then possibly. I strongly suggest you consult with a local attorney concerning this matter, and take any paperwork you have received from them.

Whether they can sue you depends. If you signed something, then yes, it is possible. Sometimes, if you drop someone off at a treatment facility, they will have in the fine print that you agree to pay. So if your hand ever touched a pen and you signed anything, even if you didn't think it was a bill, there might be liability. On the other hand, if you did not, you may have not only defenses but counterclaims that you could allege. You will want to speak to a debt defense attorney. Most treatment facilities charge $10k plus so I doubt this is a small bill.

Unless you agreed in writing to guaranty the debt, the answer is most likely no.

General agreement with all the other attorney posters. However, you should know that if you have not executed anything which would attach liability, and there is no other obscure issue, you may have claims rooted in the Fair Debt Collections Practices Act. Call a consumer law attorney. We handle cases nationally, and there is never an out of pocket cost to our client. Call the Law Offices of Michael Lupolover, P.C. today - 201-461-0059. Mention your question...