Plea bargaining in the United States
The constitutionality of plea bargaining was established by "Brady v. United States" in 1970, although the Supreme Court warned that plea incentives which were sufficiently large or coercive as to over-rule defendants' abilities to act freely, or used in a manner giving rise to a significant number of innocent people pleading guilty, might be prohibited or lead to concerns over constitutionality. "Santobello v. New York" added that when plea bargains are broken, legal remedies exist.
Plea bargain
Italy has a form of bargaining, popularly known as "patteggiamento" but that has a technical name of penalty application under request of the parts. In fact, the bargaining is not about the charges, but about the penalty applied in sentence, reduced up to one third.