All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
It is permissible to watch such trials. The fact that this trial is being held in a court run by man-made laws does not constitute a valid reason for deeming watching it impermissible.
However, it is better for a Muslim not to do so as long as watching or attending such a trial does not benefit him. Instead, a Muslim should preoccupy himself with what benefits him in this worldly life and the Hereafter. For more benefit, please refer to Fatwa 86533.
Allaah Knows best.