At the same time, the state court system is considering providing judges with a new tool to ensure that prosecutors turn over potentially exculpatory information.
The disadvantage that defendants face in New York has begun to draw more attention, said Carlton Berkley, a retired New York City police detective. He leads Discovery for Justice, a Bronx group founded in 2013 to oppose the discovery rules that some critics deride as New York’s “blindfold law.”
“When I was a cop, I always believed the criminal justice system was on the level,” said Mr. Berkley, who was a critic of some departmental practices and who has four brothers who have served time in prison. “I’m embarrassed now to say that.”
The efforts in New York reflect a national trend toward more open discovery laws. Ohio broadened its laws in 2010. New Jersey and Utah now require that discovery be provided before a guilty plea. The American Bar Association, whose standards often serve as models for state laws, has convened a task force to update its criminal discovery standards for the first time in more than 20 years.
Even in New York, some prosecutors already go beyond what the law requires. The Brooklyn district attorney’s office has long provided open and early discovery in most cases. The acting district attorney, Eric Gonzalez, said his office sometimes sought protective orders to shield vulnerable witnesses or, more rarely, to relocate them.
“We’ve been able to find the right balance in how to keep our witnesses safe and also make sure the process is as transparent and open as possible,” Mr. Gonzalez said.
State lawmakers, facing resistance from prosecutors, have been reluctant to follow that tide.
Prosecutors describe frightening encounters between the accused and witnesses and warn of violence in a “no snitching” culture intensified by social media. Prosecutors say the current law helps protect witnesses by allowing them to withhold witness information indefinitely, since so few cases go to trial.
Jack Ryan, the chief assistant district attorney in the Queens district attorney’s office, recalled a recent case in which a witness was photographed on his way into the courthouse.
“Before the witness even testified, that video was uploaded on Facebook identifying the guy as a snitch,” Mr. Ryan said. “There’s a legitimate fear.”
‘Our Guy Was Going to Prison’
Mr. Cedres and his lawyer, Kristin Bruan, said that at…