When used to describe a crime, the word “deliberate” refers to the mental state of the person who commits the crime. It has nothing to do with the actions that are actually carried out by the individual. All that matters is the mental state of that person.
In order for an act to be deliberate, the person who commits that act has to have planned to do it and has to understand what they are doing. In other words, “deliberate” does not simply mean that you do something on purpose and not by accident. For example, if I get into a fight with someone and I pull a gun out and shoot them, I clearly did not do so by accident. However, this is not deliberate in legal terms because I did not plan to do it. Instead, I did it on the spur of the moment without really considering what I was doing. Therefore, my action was not deliberate. Now let us imagine that I get into a fight with someone and our fight is broken up by other people. Now I go home and I get angrier and angrier about the fight. I get my gun and I go back and shoot the person. In this situation, my act is deliberate. I had time to think about it and consider my actions. As long as I am mentally able to understand my actions, I am acting in a deliberate way.
Thus, “deliberate” in legal terms refers to an action that has been considered and understood. It refers to a situation in which a person thinks about what they are going to do, plans it, and does it.
Black's Law Dictionary joins "deliberate" with "premeditated" and defines both as: "an act that is planned and has been considered before being carried out." The Duhaime's Legal Dictionary, of Duhaime.org, Victoria, Canada, defines "deliberate" as: "An act which is neither sudden nor rash and for which an individual considered the probable consequences beforehand." West's Encyclopedia of American Law (on Gale Cengage) defines "deliberate" as: "Willful; purposeful; determined after thoughtful evaluation of all relevant factors; dispassionate."
The essence of the meaning of "deliberate" (adj. dih-lib-er-it) as in a deliberate action or a deliberate crime, is the characteristic of having been thought about in advance, planned with understanding and reasonable expectation of known consequences, and being of uncontrolled passions arising at the moment and in response to the moment. The core of the definition of "deliberate" is that the individual has taken willful, knowing, purpose-directed action under full and independent volition without sudden, dramatic, passionate, unreasoning mitigating factors driving their action.
A literary example from Edgar Allen Poe that might illustrate deliberate action would be his short story "The Tell-Tale Heart," which might be contrasted to his other short story, "The Fall of the House of Usher." The protagonist in "The Tell-Tale Heart" forms a hatred and loathing of his benefactor's eye and willfully, purposefully, deliberately plans purpose-direction action to rid himself of that eye and, in a situation where passion and sudden, dramatic factors are wholly missing, the protagonist, under his own independent volition, acts according to a plan for which consequences and the aftermath (burial) have been carefully thought out. In contrast, the protagonist of "The Fall of the House of Usher" flees from the crumbling House of Usher in the conclusion of the story with no forethought, with no consideration of consequences, with no willful purpose; he flees in the midst of sudden, passionate, dramatic mitigating circumstances to which he reacts with no deliberate intention or plan. The first protagonist did "act with a particular intent, which is derived from a careful consideration of factors that influence the choice to be made" (West on Gale Cengage) while the second protagonist acted upon sudden dramatic passion with no deliberate plan nor any consideration of consequences.
When "deliberate" is used in context of the law to denote a crime, it indicates without question that the perpetrator has thought about their motive(s) and has weighed the motive against the consequences and against the criminal punishment that will accompany the planned action and decided that acting in a criminal manner was in some way more highly motivated than the moral action of being a law-abiding citizen: they have "weighed the motives for the conduct against its consequences and the criminal character of the conduct before deciding to act in such a manner" (West on Gale Cengage). A person who acts in a deliberate manner is not a person who acts rashly, passionately, unreasoningly, or suddenly. A person who acts in a deliberate manner acts with "preconceived intention," with deliberate planning, and with reasonably full knowledge of risks, results and consequences. As Black's definition of "deliberate" indicates, "deliberate" is synonymous with "premeditated"; a deliberate action is a premeditated action.
As a final note, "deliberate" (v. dih-lib-uh-reyt) has a second application in law in which it means to "weigh, ponder, discuss; to examine, to consult, in order to form an opinion" (Black's Law Dictionary on TheLawDictionary.org). Judges and juries both deliberate upon the facts presented and come to a conclusion, making a decision about criminal actions and sentences. The U.S. Supreme Court gives a good illustration of the legal situation in which judges deliberate. The Supreme Court does not sit juries to deliberate on cases presented but rather the nine judges, one Chief Justice and eight Associate Justices, deliberate the facts of cases they are hearing and make their rulings from their deliberations. Another illustration comes from the example of the Court of England in which proceedings in the Queen's/King's Bench Division may be assigned to a Divisional Court, which is a court bench having two or more judges who deliberate the facts of the case to make rulings together.
Source: West's Encyclopedia of American Law, ©2005 Gale Cengage.