Juror Jonathan Nunn said he thought the money from the two wealthy donors were personal gifts, not campaign donations.
The jurors acquitted Edwards on one count of accepting illegal campaign contributions and deadlocked on the other five.
"Everybody's got their own beliefs based off of what they saw," Nunn told ABC's "Good Morning America." "They stood their ground. They stood by their decision and I respect that."
Trial observers said the jury's decision bore out criticism from the earliest stages of the case that it was a reach, that prosecutors went after the ex-U.S. senator without the kind of evidence that justified the charges that he masterminded a scheme to use campaign donations to hide his pregnant mistress from the public and his terminally ill wife.
"As noted by nearly every campaign finance lawyer who considered the matter, this was a lousy case," said Melanie Sloan, executive director for the campaign finance watchdog group Citizens for Responsibility and Ethics in Washington. "All the salacious details prosecutors offered up to prove that Edwards is, indeed, despicable, were not enough to persuade the jury to convict him."
Edwards faced six felony charges involving nearly $1 million provided by two wealthy political donors that was used to help hide the Democrat's mistress, Rielle Hunter, as he sought the White House in 2008. He faced a maximum sentence of up to 30 years in prison if convicted on all counts.
To convict Edwards, prosecutors needed to show not only that the candidate knew about the secret payments, which he denied, but that he knew he was violating federal law by accepting them. But the government was unable to produce any witness who said Edwards knowingly violated the law. Even former Edwards aide Andrew Young testified that Edwards told him he had consulted campaign finance lawyers who assured him the money was legal.
A former trial lawyer, Edwards was so unimpressed with the testimony against him that when the government rested, he turned to a member of his defense team and asked dismissively, "That's their case?"
When it was their turn, his lawyers presented just two days of evidence. Edwards elected not to take the stand in his own defense.
"This is a case that should define the difference between a wrong and a crime ... between a sin and a felony," Edwards' lead attorney Abbe Lowell told the jury during closing arguments. "John Edwards has confessed his sins. He will serve a life sentence for those."
Presented with no damning evidence and no obvious victim beyond the public's trust, jurors couldn't see their way to convicting the charismatic ex-candidate. Prosecutors are unlikely to retry the case, a law enforcement official told The Associated Press on the condition of anonymity because the decision will undergo review in the coming days.
Kieran Shanahan, a former federal prosecutor and Raleigh defense attorney who attended the trial, said he thought the prosecutors took their best shot with what was ultimately a very weak case.
"They got their best witnesses, their best evidence and the judge ruled in their favor on all major evidentiary issues," Shanahan said. "In the end, the jury just didn't believe them."
Steve Friedland, another former federal prosecutor who watched the case from inside the courtroom, said the jury's verdict was not surprising, considering the government had no smoking gun to prove Edwards guilty beyond a reasonable doubt.
But, he predicted, Edwards won't fare as well in the court of public opinion.
"Regardless of the decision, he still is Exhibit A for how we do not want our leaders to behave," said Friedland, now a professor at Elon University School of Law. "This is a huge victory for him, and big burden off his shoulders, but a hollow one given his astounding fall from grace."
From the start, lawyers for Edwards painted the prosecution as politically motivated. The investigation was originally spearheaded by George Holding, the then-U.S. Attorney for the Eastern District of North Carolina.
Appointed by President George W. Bush, Holding made a name for himself with criminal probes of high profile Democrats, including the state's former governor. When President Barack Obama came into office, Holding managed to forestall being replaced by a Democrat for years while the Edwards investigation was ongoing. He eventually resigned in 2011 as Edwards was indicted and soon announced his candidacy for Congress, winning in the GOP primary last month.
The final decision to prosecute Edwards was made by the Obama administration and the Justice Department's Public Integrity Section. Once highly admired, the section's reputation suffered after a corruption conviction against former U.S. Sen. Ted Stevens of Alaska was overturned in 2009 after it was found prosecutors knowingly concealed exculpatory evidence and allowed false testimony to be presented at trial.
The case against Edwards was tried by three prosecutors sent down from Washington and one prosecutor from Raleigh who had served as Holding's second-in-command. They presented 14 days of testimony and evidence, with Young their star witness.
An aide once so loyal he falsely claimed paternity of Edwards' baby and helped hide his mistress from the media for nearly a year, Young turned against his former boss and testified for the prosecution under an immunity agreement. Though the government's case recounted how Edwards repeatedly lied about his affair to both the American people and his cancer-stricken wife, the defense countered by shredding Young's credibility on the witness stand and using financial records to show the former aide and his wife kept most of the money at issue in the case, funneling it into the construction of the couple's $1.6 million dream home.
Before Edwards' prosecution, no federal candidate had been tried over payments from a third party that flowed to a mistress. Sloan said the lack of resolution in the case will likely leave candidates and regulators confused about what is and is not a legitimate campaign expense.
"The U.S. criminal justice system requires fair notice of what is and is not against the law," Sloan said. "Sadly, the Justice Department seems to have forgotten this fundamental American precept. Luckily, the jury remembered."
Associated Press writer Pete Yost contributed to this report from Washington.