I think we've gotten accustomed to the questions for spells and other magical workings to handle situations that are better handled without it. But that isn't your fault in the slightest.
That sounds like such a frustrating and overwhelming situation. I can't imagine what your friend is going through, and you're a very supportive friend for trying to help them through this.
I second what Sakura said about lighting a candle (or 3), this can also be used to send positive energies his way. If he's open to it, you might suggest meditation or aromatherapy (if he has that option anyway). Maybe light a candle or work a spell for the truth to come to light during the trial.
But beyond that, I'm afraid it's really a matter of accepting that the trial is going to happen when it will and life and until it has followed its path and reached its unknowable conclusion, it's out of their hands. Just a moment in time, and it will pass. I know they aren't particularly heart-warming words, but hopefully the earlier suggestions will help at least steady the nerves and raise a little positivity in the meantime and maybe even some clarity that all the important facts come to light so nothing important is left out.