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.
Pleading
Generally, a plea could be dilatory or peremptory. There were three kinds of dilatory plea: to the jurisdiction, in suspension, or in abatement. The first challenged the court's jurisdiction, the second asked the court to stay the action, and the third asked the court to dismiss the action without prejudice to the other side's right to bring the claims in another action or another court. A peremptory plea had only one kind: a plea in bar. A party making a plea in bar could either traverse the other side's pleading (i.e., deny all or some of the facts pleaded) or confess and avoid it (i.e., admit the facts pleaded but plead new ones that would dispel their effect). A traverse could be general (deny everything) or specific. Either side could plead imparlance in order to get more time to plead on the merits. Once the case was at issue, the defendant could reopen the pleadings in order to plead a newly discovered defense (and start the whole sequence again) by filing a plea puis darrein.