The school may discipline students for things that take place outside school, but only to a limited extent. Were the students wearing school uniforms or can they be identified with the school? Were they on the way home from school unaccompanied by a responsible adult? Did the alleged incident happen during school time, e.g. were they truanting? The school needs to establish your child was "bringing the school into disrepute" in some way. The school may NOT punish students for unrelated incidents "on their own time" unless they were idetifiable as pupils, typically wearing schol uniform. It is a grey area if a student goes home, then goes out again still wearing their uniform, because they are under the parent's control.
Also, to say it was a "final decision" before hearing the child and his parent is against all the principles of Common Law and Article 12 of the UN Convention on the Rights of the Child. I suggest you take legal advice.
I am not a lawyer, but if the school cancels the contract, how can they keep the deposit? Can you argue that this is effectively an illegal "fine" for your child's alleged bad behaviour, an allegation against which he has been unable to defend himself if the Head has already made a decision?
Contact Independent Parental Special Education Advice (IPSEA) [ https://www.ipsea.org.uk/contact-ipsea ], the National Autistic Society's School Exclusion Helpline on 080 8800 4002 or an advice service such as the Children's Legal Centre. Maybe start with the Exclusions Officer at you local education authority and/or the SEND Team.
You can use the school complaints policy - which they must publish on their web site. If you are not satisfied with the response from the HT there is usually an appeal to the governors. Once you have tried local resolution you can go to SENDIST and/or complain to Ofsted. Given that the HT has already made a "final" decision there might be grounds for going straight to SENDIST - as I say, take expert advice. The school will need to establish that they have considered all the factors - this involves a full risk assessment, have they considered providing additional support for your child? If they can prove it was "not reasonably practicable " or would have a negative impact on the education of children they may have a reasonable excuse, but they need to have done the necessary risk assessments.
I am guessing it is the end of term and the trip has taken place ... please let us know what happened. Even after the event, you can still make a discrimination complaint. Head Teachers may think they are above the law, but they are not.
(Joke > Do you know the difference between a Head Teacher and God? God does not think he is a Head Teacher.)
I agree with the other responses about how to approach the school about the trip, but there is something to be said for sitting down with your son to talk about actions and consequences.
The brains centre which deals with this automatically does not fully develop until your 20's so you need to be able to try to make your son think through this conciously for now.
If you can do it in a way that is more of a review of the situation, learn the lessons and think about how to do it in future then that would be the most effective way. Avoid blame and emotion as he will probably find this difficult to process and may just block it out.
Done like a lesson it will hopefully have some impact, but being of that age I suspect it will be forgotten more often than not, but on the few occasions when he does think, it may just save his bacon.
Good luck with the school and I hope he gets to go on the trip in the end.
Bad behaviour??!! Are the school taking the mick?? So they are being abliest against a child who is medically diagnosed with asd and adhd.
Report to ofsted and the local authority. This is not OK. You cannot punish a child who may not have the social ability and easily led by others.
I'm actually really peed off for you, exclusion still happening to children with additional needs in this day and age!!
and a couple of friends, made a silly decision, out of school, (went somewhere they shouldn't) which, had they been caught, would have probably resulted in a telling off by the police
It sounds like your son isn't the only one engaging un reckless behaviour, so if these other kids have not also been told they cannot go, and the school can't tell you the exact scenario they feel they would not be able to keep your son and others safe in then yes their decision is discriminatory. Especially because up until that point they were perfectly happy to take your money and felt he was not a risk so offered him a slot on the trip in the first place.
I would ask if the other children involved in the incident have received the same treatment. If they have not it would seem that the school's actions amount to discrimination on the grounds of disability. I would write a formal letter to the headteacher, and cc the chairman of the governors and whatever body they report to (local education committee etc.) about your suspicion of discrimination and also ask for a copy of the risk assessment that they should have produced before deciding to exclude your child. If you can afford to have a solicitor write a letter on your behalf, so much the better.