Plea bargaining is an agreement in criminal proceedings between the prosecution and defence that involves the exchange of punitive leniency for a guilty plea or its legal equivalent. Defendants may enter into plea agreements through traditional guilty pleas, nolo contendere (no-contest) pleas, and Alford pleas. In a no-contest plea, the defendant concedes that the evidence is sufficient for a finding of guilt but does not make a formal statement of guilt, while an Alford plea allows the defendant to maintain innocence while conceding that the evidence is sufficient for a finding of guilt. Regardless of the type of plea, however, plea agreements are only considered valid when entered into knowingly, intelligently, voluntarily, and with a factual basis of guilt. Plea bargaining is often discussed in the context of the U.S. criminal justice system, where it came to prominence in the early twentieth century and has become the most prevalent form of case disposition, accounting for roughly 95% of convictions in state, federal, and juvenile courts. However, plea bargaining and similar types of legal processes are on the rise internationally in countries such as Russia, China, Germany, Italy, and France. Given the increasing prevalence both in the U.S. and internationally, plea bargaining has garnered increasing attention from scholars. While, in theory, plea bargaining is a resource-saving tool for both the defendant and the criminal justice system, as it expedites case resolution and mitigates punishment, it has become increasingly apparent that many defendants do not comprehend the agreements they enter into, and that innocent defendants are pleading guilty at an alarming rate. Researchers and critics alike have suggested that the vast incentives offered in plea agreements can entice even innocent defendants to plead guilty to avoid the risk of a conviction at trial and the concomitant harsher penalties. Likewise, the pressured circumstances in which defendants must make these decisions have led some to question whether any decision made in this environment can be considered voluntary. These issues are compounded with observational research suggesting that many defendants do not fully comprehend the conditions of their agreements or the rights they are giving up. Less cognitively mature populations of defendants, such as juveniles, have been shown to be particularly at risk. Thus, while perhaps superficially sound and practised extensively, there is amassing evidence to suggest that plea bargaining may create systematic issues with the legitimacy of criminal justice outcomes.