The New York state legislature has passed a reform package aimed at increasing fairness in the criminal justice system.

The new law requires prosecutors to share evidence against criminal defendants within 15 days of arraignment, a major shift for a state that previously had no such deadlines and maintained a notably restrictive approach toward disclosure.

New York defense lawyers have long complained of “trial by ambush,” where prosecutors were allowed to deliver crucial evidence at late stages of criminal proceedings, forcing defendants and their lawyers to make difficult decisions about whether to accept a plea deal or take their chances at trial based on limited information.

The reform package “will end the gamesmanship and power dynamics that have favored prosecutors for decades, resulting in thousands of coerced pleas and wrongful convictions,” said Janet Sabel, CEO of Legal Aid, calling the changes “monumental.”

In 2013, ProPublica published a series of articles on prosecutorial misconduct in New York City. We examined nearly 30 cases where appellate courts had overturned convictions because prosecutors committed some form of ethical or legal violation. In many of those cases, law enforcement failed to turn over evidence that was favorable to the defense.

In one such case, prosecutors withheld a receipt showing a man was on vacation in Florida at the time of a murder he was convicted of in Brooklyn. In another, prosecutors said a witness had testified of his free will, when in fact he had been arrested, held in a hotel room overnight and threatened with jail time before ultimately agreeing to appear in court as the state’s single eyewitness in a murder trial. In that case, prosecutors kept from the defense a material witness order — a powerful legal document signed by a judge and used as a last resort to compel reluctant witnesses to testify.

Joel Rudin, a New York defense attorney who represented several of the people wrongfully convicted in these cases, said the bill marks “the most important development in the criminal justice system” in his 40-year career.

One of those cases was that of Jabbar Collins, who served 16 years in prison for a crime he did not commit. He and Rudin accused a senior Brooklyn prosecutor of coercing a witness, withholding evidence and suborning perjury to win his conviction in 1995. Ultimately, the pair of them won $13 million in settlements from New York City and state.

In a statement, Rudin said it was unclear whether the new law would have necessarily forced prosecutors in the case to act differently, but he pointed out that it does provide far more specifics on what needs to be turned over and when.

Under the new law, prosecutors must collect and share all police reports, witness statements, electronic recordings, grand jury transcripts, any and all electronic recordings, 911 calls, crime scene photographs, lab reports, expert opinion evidence and other material. If prosecutors fail to share such information within the specified time frame, a court may issue sanctions.

Already, the U.S. Supreme Court’s 1963 Brady v. Maryland decision requires prosecutors to disclose exculpatory evidence. But this new law expands that obligation and establishes strict timelines to fulfill it in New York. Now, prosecutors must turn over their entire evidence file, regardless of whether the prosecutor believes certain information in it to be exculpatory. To keep anything from the defense, prosecutors must convince a judge that the evidence could be used to harm a prospective witness.

The bill is part of a larger criminal reform package that vastly reduces New York’s use of cash bail and removes impediments to speedy trials. Advocates and Democratic leaders have been pushing such measures for years. They were finally able to do so by including it in the state budget, which passed under the new Democratic majority in the legislature a week ago.

Prosecutors had long argued that such reforms would slow justice and potentially harm victims and witnesses. Some district attorneys accused the legislature of using underhanded tactics to get the deal done.

“While most New Yorkers were sleeping and enjoying the weekend, a handful of lawmakers with limited knowledge of the criminal justice system, behind closed doors, came to an agreement that will place unnecessary burdens on the workings of our criminal justice system and actually slow down the wheels of justice,” said Albany County District Attorney David Soares, president of the statewide district attorneys association.

Marvin Schechter, a veteran New York City defense lawyer and former chairman of the criminal justice section of the New York State Bar Association, welcomed the change. But, in an emailed statement, he also cautioned that courts have chipped away at similar, previous moves toward reform.

“Past efforts to reform New York’s antiquated and severely restrictive discovery statutes have been hailed as transformational and even progressive only to fail in an avalanche of court decisions blocking discovery from reaching the accused,” he wrote. “Only time will tell if the commitment to a more transparent and open system… will take hold.”

For their part, many district attorneys throughout the state are worried that the new law will strain law enforcement and the courts.

“Our hope was that our lawmakers would heed some of the suggestions by prosecutors concerning the procedure involved in the bills related to bail, discovery and speedy trial,” said Soares, the state district attorneys association president. “Instead, they have set up unrealistic, unworkable requirements that ultimately will fail the very people and communities they were intended to benefit.”