"We are referred to substantial medical authority that [partial-birth abortion] perverts the natural birth process to a greater degree than [D&E], commandeering the live birth process until the skull is pierced. Witnesses to the procedure relate that the fingers and feet of the fetus are moving prior to the piercing of the skull; when the scissors are inserted in the back of the head, the fetus' body, wholly outside the woman's body and alive, reacts as though startled and goes limp. [Partial-birth abortion]'s stronger resemblance to infanticide means Nebraska could conclude the procedure presents a greater risk of disrespect for life and a consequent greater risk to the profession and society, which depend for their sustenance upon reciprocal recognition of dignity and respect. The Court is without authority to second-guess this conclusion."