Court date; will I be able to assist?

You typing a note may not work. I would get his PCP or if he goes to a specialist him/her to write a letter explaining ur SO has a stuttering problem which gets worse when he is upset or nervous. If the ticket is this high because he couldn't respond, maybe the letter will help to lower the fine. I would consider this a disability like someone who is deaf. Call the court clerk and tell them of the problem and if you can be his voice.

In the future, I would have him carry a letter from the doctor in his glove compartment.

Ring the court, explain to the officials that your husband has a speech impairment which becomes worse under stress, and they will advise you what to do. It's probably just a matter of ensuring that whoever is involved in the hearing is aware that he will need allowances made for his difficulties.

I don't know if this is true in your jurisdiction, but there is also such a thing as a "next friend" - a person with no professional status but who stands in the participant's corner and lends support. Might be worth asking about.

Anyway - the court's officers are the people to consult, and such people are usually very helpful to ordinary members of the public. It serves justice for everything to be done fairly, after all, and they are servants of the justice system.

Does your husband see a speech therapist?

I think I would type up a note with an outline of the diagnosis and hand it to the clerk of the court.