"The admission of defendant's rap writings bore a high likelihood of poisoning the jury," the court said.
Skinner was convicted of shooting Lamont Peterson in the head, neck, and torso at close range in 2005, leaving him paralyzed from the waist down. Skinner was sentenced to 30 years in prison.
In 2012, an appellate panel determined that the use of the rap lyrics at Skinner's trial was prejudicial. It ordered a new trial. The state appealed that decision to the Supreme Court.
The case is one of about 20 across the country dealing with the admissibility of rap lyrics at criminal trials.
Ezra Rosenberg, an American Civil Liberties Union lawyer who intervened in the case, hailed Monday's ruling as the "most thorough and in-depth analysis of the issue I've seen."
"This is a victory for free expression," Rosenberg said. "It recognizes that artistic expressions must be dealt with differently."
The justices urged extreme caution when considering the value of expressive work in a trial, especially when it involves social commentary, exaggeration, and fictional accounts.
"One would not presume that Bob Marley, who wrote the well-known song 'I Shot the Sheriff,' actually shot a sheriff, or that Edgar Allan Poe buried a man beneath his floorboards, as depicted in his short story 'The Tell-Tale Heart,' simply because of their respective artistic endeavors on those subjects," Justice Jaynee LaVecchia wrote.
At his trial, Skinner was implicated mainly by his alleged victim, who identified Skinner as the "muscle" in a three-person drug gang in Willingboro that included both men and a leader. No gun was recovered.
Skinner admitted to police that he was at the scene of the shooting and said he heard a shot fired but was not the shooter. Peterson testified that he had been skimming profits from the drug business.
Prosecutors turned to Skinner's rap lyrics, found in notebooks in his car, to establish his state of mind.
In the lyrics, Skinner refers to himself as "the Threat," and in one line he writes: "Yo, look in my eyes. You can see death comin'. Look in my palms, you can see what I'm gunnin' with."
During oral arguments in April before the Supreme Court, none of the five justices who had questions indicated support for the prosecutor's arguments.
"The admission of defendant's inflammatory rap verses, a genre that certain members of society view as art and others view as distasteful and descriptive of a mean-spirited culture, risked poisoning the jury against defendant," the Supreme Court said in Monday's ruling.
In a statement, Burlington County Prosecutor Robert D. Bernardi said: "We appreciate the court's direction going forward on the use of such lyrics. This decision provides guidance to all New Jersey prosecutors who contemplate the use of such evidence in the future. We stand ready to retry Mr. Skinner on his outstanding attempted murder charge."
Skinner remains in custody on $250,850 bail. A first appearance will be scheduled soon in Superior Court, where his bail will be reviewed, Bernardi said.