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.
Bargaining
In almost all large complex business negotiations, a certain amount of bargaining takes place. One simplified 'western' way to decide when it's time to bargain is to break negotiation into two stages: creating value and claiming value. Claiming value is another phrase for bargaining. Many cultures take offence when they perceive the other side as having started bargaining too soon. This offence is usually as a result of their wanting to first create value for longer before they bargain together. The Chinese culture by contrast places a much higher value on taking time to build a business relationship before starting to create value or bargain. Not understanding when to start bargaining has ruined many an otherwise positive business negotiation.