Exclude, or not?
A The Disability Discrimination Act 1995 was amended from September 2002 by the Special Educational Needs and Disability Act 2001 to introduce new rights for disabled children in schools. Although these rights have been in force for two years, there have been relatively few cases to explore the extent of the obligations. The Act covers all disabled people, but the definition of disability is different from the definition of special educational needs in education law so that not all children with special educational needs will be "disabled" for the purposes of the DDA.
Broadly speaking, disabled people have a right not to be treated less favourably for a reason relating to their disability without justification.
Their schools are required to make a reasonable adjustment to overcome any substantial difficulty that disabled pupils might face, arising from their difficulty.
In this case, if you decide to exclude this child because of the way he lashes out, the first question in considering whether the DDA comes into play is whether he is a disabled person. If he is, the next question is whether his behaviour is directly related to his disability or not. If it is, it is certainly the case that excluding him is "less favourable treatment" so, arguably, it could be unlawful.
However, the key issue will then be whether you are justified in doing so (a question of law), so that you will not be acting unlawfully.
Clearly, the well-being of other pupils and staff will be a key consideration for this and providing that you have a genuine concern about it, it is unlikely that your actions will be unlawful. However, before you decide to exclude him, you should certainly consider whether there are any steps (short of exclusion) that you may take to ameliorate the difficulties.