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Former North Charleston police officer Michael Slager, right, sits in the courtroom during his murder trial at the Charleston County court in Charleston, S.C., Friday, Dec. 2, 2016.
The trial of a former South Carolina police officer accused of murdering Walter Scott, an unarmed black man, was declared a mistrial on Monday after the jury failed to unanimously reach a verdict despite 22 hours of deliberation.
Michael Slager is facing a maximum sentence of life in prison for his role in the 2015 killing of Scott. The jury was also allowed to consider a lesser charge of manslaughter, for which Slager would be sentenced to a maximum of 30 years if convicted.
What is a mistrial?
A mistrial is a trial that has not reached its normal conclusion, has no legal consequences and is considered invalid. Though there are a number of factors that can result in a mistrial, like lack of jurisdiction and incorrect jury selection, a hung jury - a jury that's unable to unanimously come to a verdict - is the most common reason.
The unanimous jury verdict has long been considered a "defining feature" of jury trials, according to Jeffrey Abramson in "We, the Jury," dating back more than 600 years in England. Such was the case in the United States up until 1972, when the Supreme Court ruled in Apodaca v. Oregon that a state jury could convict a defendant by a less-than-unanimous margin, though a federal jury must still agree unanimously.
However, all but Louisiana and Oregon currently require a unanimous verdict for criminal trials. South Carolina requires an unanimous verdict in criminal trials.
In Slager's trial, the jury was not able to unanimously convict him, and one juror wrote a note to the judge saying that he "cannot and will not" declare Slager guilty of murder or manslaughter.
"Judge, I understand the position of the court but I cannot in good conscience consider a guilty verdict," Newman read out loud in the courtroom. "I expect those who hold opposing views not to change their minds because I see them as good, honest people."
"Therefore, I regret to say we may never reach a unanimous decision."
What happens in the event of a mistrial?
When a mistrial is declared, it is up to the government to decide whether it wants to drop the prosecution or attempt a retrial.
Scarlett A. Wilson, prosecutor for Charleston County, said in a statement that her office intends to put Slager on trial once more.
"We will try Michael Slager again," Wilson said. "We hope the federal and state courts will coordinate efforts regarding any future trial dates but we stand ready whenever the court calls."