Q: Can an autistic adult be questioned by police after an arrest without a lawyer present?

A: Maybe. Not all people with autism are incompetent. They talk about the 'autism spectrum.' This means that there are people with a wide variety of capabilities who are afflicted with autism. What you are really asking is whether the police can question a person who is mentally handicapped without the presence of a lawyer. The answer is still, 'Maybe.' Everything is going to depend on the reasonableness of the police actions. A person cannot be compelled to give evidence against himself. This is the protection of the Fifth Amendment to the US Constitution as made applicable to the States through the Due Process Clause of the Fourteenth Amendment. If police obtain a statement from a person and the statement was not given voluntarily, then the courts will not allow that statement to be offered as evidence in a trial. This is known as the "Exclusionary Rule." When a person is in the custody of the police, the courts presume that there is a certain amount of coercion involved, at least psychologically speaking. In order to dispel this coercive atmosphere, police are required to warn the people they arrest about the right to remain silent and the right to have an attorney present before they, the police, take any kind of statement from the arrestee. These are the warnings we call the 'Miranda Rights." If a person is incapable, because of intoxication or incapacity to understand this warning, then it cannot be said that they have 'waived' or given up those rights. However, there is no bright line rule requiring that if a person has a particular disability none of their statement to the police are admissible evidence. Each case will depend on its own facts. You need to rely on the lawyer representing you, or whoever the autistic person is, to bring this matter to the attention of the judge.