HUNG JURY

A jury that is unable to reach a verdict which, if it persists, usually results in a mistrial being declared by the court.

In such a situation the case may be retried, generally at the discretion of the prosecution if criminal. In such a situation a retrial does not constitute double jeopardy.

In the interests of justice and judicial economy most courts will attempt various means to allow/persuade a jury to continue deliberating and only declare a mistrial when certain the jury is incapable of reaching a verdict.

A jury is required to make a unanimous or near unanimous verdict. - (read more on Hung jury)
  

One whose members cannot reconcile their differences of opinion andthat therefore cannot reach a verdict by the degree of agreement required(generally unanimity, but sometimes a substantial majority).