The snap verdict came after nine months of testimony, with over 100 witnesses. Adding to the drama of the world's most-watched trial, and demonstrating his old flair for publicity, Judge Ito delayed the verdict overnight to allow lawyers for both sides to return to the courtroom.
Assuming the jury have genuinely agreed a verdict, they have confounded months of conventional wisdom that a racially charged case would end in a divided jury and stagger towards a mistrial or acquittal. The instant reaction of legal commentators in the US was that an early decision boded ill for Simpson but they have been wrong before.
The jury has a choice of first and second degree murder charges against Simpson, accused of brutally knifing his ex-wife Nicole and visiting waiter Ronald Goldman to death, then launching into a convincing cover-up of his crime.
Earlier in the day jurors asked for the testimony of Allan Park, a chauffeur and key witness for the prosecution, to be read back to them. Park's evidence, backed by records from his car-phone, was critical in establishing the prosecution's chronology for the murder.
He was never tied to the far-ranging racist conspiracy in the Los Angeles police department conjured up by the defence, which claimed that Officer Mark Fuhrman had planted key evidence including the famous bloody glove, against Simpson. But it is notoriously difficult to read juries' intentions from their questions about evidence.
After a parade of seedy Hollywood hangers-on, racist cops, well-heeled defence lawyers invoking the Bible, and prosecutor Marcia Clark's revolving hair-dos, O J's fate has been handed to a collection of ordinary people - postal workers, local government employees - dominated by black women.
The jury includes eight black women aged 24 up, seven employed and one retired, two white women, and two men - a black phone company salesman, and a Hispanic Pepsi truck driver. Polls outside the courtroom suggested that while whites were convinced of O J's guilt most blacks were not.
Trial commentators had predicted the jury would spend their early days venting feelings and thoughts they were barred from expressing through nearly nine months of testimony. Instead they rapidly agreed on a forewoman, a 50-year-old black woman, an LA administrative worker. A mere three hours after starting deliberations they asked for Park's testimony.Reuse content