The jurors who will be chosen to hear the first case against a police officer charged in the death of Freddie Gray in Baltimore will be anonymous, at least for now.

A judge has ruled that their identities can be shielded from the public. That practice is controversial, but not unheard of in high-profile cases.

Experts trace the first completely anonymous jury — secret not just to the media, but also to the defendant — to 1977. That's when a judge worried about possible jury tampering by a drug kingpin named Leroy "Nicky" Barnes, a man also known as Mr. Untouchable.

"They tend to be only used in very, very high-profile trials or trials in which there is a serious threat to either the safety of the jurors or the integrity of the jury process," said Paula Hannaford-Agor, who studies jury issues at the National Center for State Courts.

Hannaford-Agor said there are plenty of examples in recent years of a more limited approach: keeping juror names from the public and the press during the trial but releasing the information later. She said courts recognize a legitimate need to protect the jury.

"There are issues associated with this; this is not necessarily a risk-free civic engagement," she said.

By issues, she meant everything from reporters with TV cameras turning up at a juror's door late at night to death threats from neighbors unhappy about the verdict.

That happened in Florida in 2011, when a young woman named Casey Anthony was acquitted of murder in the death of her daughter.

"Vendors were putting up signs in their windows, 'Casey Anthony jurors not welcome here.' One juror essentially left the state because she was actually afraid for her life," Hannaford-Agor recalled.

First Amendment scholars worry that secrecy once reserved for cases of gang activity and terrorism has been extended to jurors in lots of other contexts.

Cases in point: the corruption trial of former Illinois Gov. Rod Blagojevich and the prosecution of George Zimmerman, the self-described neighborhood watchman who killed Trayvon Martin in Florida three years ago.

In the prosecution of Baltimore police Officer William Porter, his lawyers wrote that potential jurors could face a lot of pushback from the community.

"In the current climate, saying 'not guilty' regardless of the evidence or the lack thereof presented by the state, and then returning to your daily life will take great courage on the part of the citizenry," wrote attorneys Joseph Murtha and Gary Proctor. "It is possible, indeed probable, that an acquittal of Officer Porter will lead to further civil unrest. But this officer deserves his trial without any 'sacrificial lamb' thinking on the part of jury members."

Gregg Leslie closely follows media law issues as legal defense director at the Reporters Committee for Freedom of the Press.

"If you start by default having jurors who are secret even well after the trial, it really will start to and in fact it has I think started to have an effect on how the public perceives how just the system is," Leslie said.

Leslie pointed out that the nation is already debating the fairness of the justice system, in part because of the deaths of young black men like Freddie Gray in encounters with police.

Leslie said transparency as these cases move through the courts will help restore credibility. It's true that jurors may be exposed to unwanted attention, with some cost to their privacy, at the end of a trial, but Leslie said too much secrecy also has a cost.

"When secrecy becomes the norm, some of those jurors will be less candid in voir dire, figuring they'll never be held accountable for it," Leslie said, "so secrecy breeds greater corruption and greater problems within the system."

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