Mayor Bill de Blasio hoped to curb traffic injuries and deaths with his citywide Vision Zero initiative. View Full Caption DNAinfo/Katie Honan

QUEENS — A key part of the mayor's landmark pedestrian and bicycle safety initiative that penalizes drivers for hitting people is unconstitutional, a judge ruled Friday.

Queens Supreme Court Justice Gia Morris ruled that Mayor Bill de Blasio's Vision Zero charge, failure to exercise due care, violates defendants' right to due process as protected by the United States Constitution — saying the law puts the burden of proof on drivers to show they weren't driving negligently, which violates their presumption of innocence under the Fifth and Fourteenth amendments.

Morris' ruling came as part of a case against school bus driver Isaac Sanson, who fatally struck 85-year-old Jeanine Deutsch as she crossed the street in Forest Hills.

Sanson had just dropped off two kids at 108th Avenue and made a right turn onto 70th Road when he hit Deutsch in the crosswalk about 1 p.m. on Dec. 19, 2014, his passengers told prosecutors.

The Queens District Attorney has not yet decided whether to appeal the ruling by Morris, who was appointed by Mayor Michael Bloomberg.

"We are studying the decision and weighing our appellate options," said spokesman Kevin Ryan.

A spokesman for the de Blasio's office denounced the ruling and said that they plan to continue to encourage NYPD officers to use the city's administrative code 19-190, or failure to exercise due care.

"[The Vision Zero misdemeanor] is a vital tool to hold accountable drivers who seriously injure or kill pedestrians with the right of way while driving dangerously. This is an important piece of Vision Zero's comprehensive approach to reducing death and serious injury on our streets. We disagree with the court's non-binding decision and will continue to investigate, enforce and charge this law," said spokesman Austin Finan.

Morris' decision is the latest blow to de Blasio's central traffic safety plan that's faced strong opposition since it was rolled out with much fanfare in 2014.

Safety advocates worry the decision could have "a chilling effect" on traffic prosecutions in the city.

"They’re not automatically compelled to throw these cases out, but that’s a concern. One of the most important pieces of legislation to come around to make our streets safer could lose its effect," said Peter Beadle, an attorney with a leading traffic safety advocacy law firm, Vaccaro and White.

"Hopefully, the police and District Attorneys will continue to apply this law. It would be a travesty if it was discarded over this."

► Read the decision below.

Morris' ruling comes on the heels of another judge's January ruling defending the constitutionality of the 19-190 law.

In January, Manhattan Judge Ann Scherzer rejected arguments from driver MD Hossain, who became the first driver charged with the misdemeanor after killing an MMA fighter's mother on the Upper East Side, that the law was unconstitutional.

"To successfully challenge ... 19-190, defendant would have to demonstrate beyond a reasonable doubt that the statue is unconstitutional by imposing an unacceptable and unjustified restriction on a constitutional right, failing to provide notice of what conduct is prohibited, or by encouraging or permitting arbitrary or discriminatory enforcement. None of defendant's arguments come close to meeting that heavy burden," Scherzer wrote.

Police — who critics said were initially slow to use the law against drivers — are on track to arrest more bad drivers than ever on Vision Zero charges with 63 percent more busts than this time last year, according to NYPD data.

They've arrested 18 drivers for failing to exercise due care behind the wheel as of June 10 — 63 percent more than they had arrested by this time last year. Fourteen of those drivers were responsible for fatal crashes, police said.

That's just two arrests shy of the 2015 total and more than all of 2014 when the law went into affect, data shows.

There have been 53 pedestrians and cyclists killed by drivers from the beginning of the 2016 through June 10, police said.

Map: Crashes where drivers were arrested on Vision Zero charges.

Among the drivers who have been arrested this year include Joseph Cherry, who was behind the wheel of a fuel truck that fatally struck a Bushwick cyclist on June 7 while driving on a road where trucks weren't allowed, NYPD officials said.

The death sparked a crackdown by the NYPD on truck drivers who strayed outside of designated truck routes — leading to 125 tickets in 72 hours.

Previously, DNAinfo found that by the end of 2015, only 15 percent of drivers involved in fatal crashes were ever slapped with the Vision Zero charge.

Staten Island, where no driver had been arrested under Vision Zero, saw three arrests this year, including Luigi Tucci who fatally struck Maria Serrano while she walked her dog, Oscar.

The Transit Workers Union strongly opposed the mayor's effort after 6 city bus drivers were arrested and charged following accidents.

John Samuelsen, president of the TWU Local 100, lauded the decision Tuesday.

"The judge clearly, forcefully and correctly has ruled that Bill de Blasio essentially trampled on the constitution, and on the rights of hard working, conscientious Bus Operators," Samuelsen said. "The judge has validated TWU Local 100’s objection to these wrongful arrests in the aftermath of accidents."

With reporting by Nigel Chiwaya.

Judge Rules Vision Zero is Unconstitutional by DNAinfoNewYork