noun, masculine/pʁɔ.sɛ d‿ɛ̃.tɑ̃.sjɔ̃/
instance of dismissing a claim by questioning someone's motives; appeal to motive; act of speculating on someone's intentions and judging them, as if it were a trial for the crime of having said intentions
“faire un procès d'intention à quelqu'un” — to question someone's motives; to impute motives to someone
Literally, “trial of intention”. Compare Italian processo alle intenzioni.