My [redacted by Moderator] is on a list of names that have been summoned to court as witnesses to a crime. He is not able to go on this day as he has a prior engagement that is more important.
What does he do about it?
Thanks for your help.
I would suggest contacting the party summoning the particular person as well as the court in question. Depending on what the prior engagement is (it would have to be quite important), the court may be willing to come to some sort of alternative arrangement.
Is your son a lawyer for the prosecution, or defendant? Either one, contact the party you have been subpoenaed from and inform them of this. If the information your son is expected to give is required for the case, they may seek an adjournment (postpone the hearing).