In most United States jurisdictions a defendant is allowed the opportunity to allocute—that is, explain himself—before sentence is passed. Some jurisdictions hold this as an absolute right, and in its absence, a sentence may potentially be overturned, with the result that a new sentencing hearing must be held.
Allocution is sometimes required of a defendant who pleads guilty to a crime in a plea bargain in exchange for a reduced sentence. In this instance, allocution can serve to provide closure for victims or their families. In principle, it removes any doubt as to the exact nature of the defendant's guilt in the matter. However, there have been many cases in which the defendant allocuted to a crime that he did not commit, often because this was a requirement to receiving a lesser sentence.
The term "allocution" is generally only in use in jurisdictions in the United States, though there are vaguely similar processes in other common law countries.
For example in Australia the term "allocutus" will be used. It will be used by the Clerk of Arraigns or another formal associate of the Court. It will generally be phrased as "Prisoner at the Bar, you have been found Guilty by a jury of your peers of the offense of XYZ. Do you have anything to say as to why the sentence of this Court should not now be passed upon you?". The defense counsel will then make a "plea in mitigation" (also called "submissions on penalty") wherein he or she will attempt to mitigate the relative seriousness of the offense and heavily refer to and rely upon the defendant's previous good character and good works (if any). In Australia, the right to make a plea in mitigation is absolute. If a judge or magistrate were to refuse to hear such a plea, or obviously fail to properly consider it, then the sentence would, without doubt, be overturned on appeal.
In many other jurisdictions it is for the defense lawyer to mitigate on his client's behalf, and the defendant himself will rarely have the opportunity to speak.
Allocution refers to the one way dissemination of information through a media channel. It assumes that one party has an unlimited amount of information (usually through some kind of expertise) and can act as the ‘information services provider’ (pg 268) while the other party acts as the ‘information services consumer’ (Bordewijk and Kaam, 1986:268)
The term allocution differs from distribution as distribution implies that the original party loses some kind of control over the information. One party can tell many others a piece of information without losing it themselves, the original information store never becomes empty. (Bordewijk and Kaam, 1986:268)
The original party holds all control over the information. They decide when, how and how much information to give to the information services consumer. The consumer has no control over it in this model.
Examples of this type of communication include radio and traditional television programs such as the news.
Bordewijk, Jan L. and van Kaam, Ben (2002)  “Towards a New Classification of Tele-Information Services,” in Denis McQuail (ed.) McQuail’s Reader in Mass Communication Theory, Sage, London, pp.113-24