Depending on how it is pronounced, deliberate may either be a verb or an adjective.
When pronounced as "deh-LIH-ber-uht," it is a descriptive term meaning "purposeful;" it is an antonym for "accidental."
For example, when one person injures another by beating them with a baseball bat, the action is considered to be deliberate. If this person injured the second party in the course of a game by carelessly tossing the bat after hitting the ball and making the run, it would be considered accidental. S/he may still be held liable under civil law however, should the victim choose to file suit.
When pronounced as "dee-LIH-ber-ate" (rhyming with "eight"), it means to consider a matter carefully. For example, when a judge is called upon to issue a ruling in a particularly difficult and complex case, s/he may retire to his/her chambers to deliberate over the decision. When a jury retires from the court to consider evidence and issue a ruling (called a "verdict" in criminal trials), it is said to be in deliberation. Again, this deliberation can take anywhere from a few minutes to several weeks, or even months depending on the issue(s), the amount of evidence to consider, and the complexity of the case.
If a jury is unable to make a decision, the jury is considered "hung," and the judge will declare a mistrial. In this case, a new jury is selected and the case is retried. In criminal cases, a jury verdict is required to be unanimous; however, in civil litigation, there needs only be a majority consensus. Some jurisdictions give parties to a court action a choice between a six-person and a twelve-person jury; since a larger number of people increases the chances of dissension, the counsel for the defense - whether representing an accused criminal or the defendant of a civil action - will lobby for the larger number of jurors, since a hung jury, while less desirable than a favorable ruling, is preferable to losing a case altogether.