Did you serve a Notice of Claim within 90 days of the incident? Consult with a personal injury lawyer.
The above answer, and any follow up comments or emails is for informational purposes only and not meant as legal advice.
Even if you didn't serve a notice of claim within the 90 day window, and depending upon how late you are, a good lawyer should be able to argue that your notice to the principal and the district removes all prejudice from the late filing. Further, it's an infant's case and courts tend to be more pro active in finding arguments to keep alive actions that might otherwise be dismissed. You need a lawyer to immediately file a motion to serve a late notice of claim, nunc pro tunc (now for then), good luck to you and your son.
We are Serious lawyers for the Seriously injured. I am a co-author of WEITZ ON AUTOMOBILE LITIGATION: THE NO FAULT HANDBOOK. The opinions expressed in this answer are not legal advice. These opinions are thoughts based on New York practice. We have no attorney-client relationship. Conducting a conversation with me through the avvo comments section does not create an attorney-client relationship. Past results are not necessarily indicative of future performance.
You do need an attorney to properly handle this matter for you. You should contact a local Education attorney immediately.
All of Ms. Riley's responses to questions posted on AVVO are intended as general information based upon the facts stated in the question, and are provided for educational purposes of the public, not any specific individual, and her response to the question above is not legal advice and it does not create an attorney-client relationship. Ms. Riley is licensed to practice law in New York. If you would like to obtain specific legal advice about this issue, you must contact an attorney who is licensed to practice law in your state.