Cy Vance’s office does not discuss vehicular crimes cases, even after they are disposed or when no charges are filed. After declining to prosecute the cabbie who drove onto a Midtown sidewalk and severed the leg of Sian Green, the DA’s office issued a short statement, but the only insight into the prosecutors’ reasoning came from the victim’s attorney, who said Vance’s team “indicated that failure to charge was due to lack of evidence regarding the taxi cab driver’s intent during the investigation phase.”

Attorney Steve Vaccaro, who specializes in representing traffic violence victims, said today he believes Vance had a reasonable chance of getting a conviction on charges of third degree assault and second degree reckless endangerment. Both are class A misdemeanors (the most serious misdemeanor category), and according to Vaccaro neither require prosecutors to prove intent.

Here are the relevant sections of state law cited by Vaccaro:

§ 120.00 Assault in the third degree. A person is guilty of assault in the third degree when … with criminal negligence, he causes physical injury to another person by means of a deadly weapon or a dangerous instrument.

§ 120.20 Reckless endangerment in the second degree. A person is guilty of reckless endangerment in the second degree when he recklessly engages in conduct which creates a substantial risk of serious physical injury to another person.

Why didn’t Vance try to secure a conviction on one of these relatively low-level charges? The public may never know.

The statement released by Vance’s office yesterday says only that after an investigation by the DA and NYPD, “we have concluded that criminal charges cannot be filed in this case.” The statement lists the type of evidence reviewed — surveillance video, 911 calls, black box data — but gives no indication why that evidence was found insufficient to support charges.

“This decision has frightening implications,” Transportation Alternatives Executive Director Paul White told the Times. “Drivers have the most responsibility, because people behind the wheel of one-ton vehicles have the greatest capacity to do harm to others. The law should acknowledge that fact.”

After failing to bring charges in this case, Vance spokesperson Joan Vollero said, “We are sensitive to the trauma faced by Ms. Green and others injured in vehicular crashes.”

Since Green was visiting from England, and strangers including celebrity doctor Mehmet Oz came to her aid, this case has gotten a lot of press in the U.S. and abroad. But every year there are thousands of similar crashes in New York that result in no charges against the motorist, without even so much as a statement from the DA. More than sensitivity, victims of traffic violence need Vance, his fellow district attorneys, and NYPD to hold dangerous drivers accountable through the force of law, whether or not they win every case.