“ The issue raised by this petition is whether a trial court may enjoin publication of information alleged to threaten a criminal defendant's right to a fair trial without any threshold showing that the information will indeed cause such harm and that suppression is the only means of averting it. ”

“ Our precedents make unmistakably clear that " ' [a] ny prior restraint on expression comes to this Court with a "heavy presumption" against its constitutional validity,' " and that the proponent of this drastic remedy " 'carries a heavy burden of showing justification for [its] imposition.' " Nebraska Press Assn. ”