Effective August 15, 2010, there are new rules in effect for all New York DWI or Aggravated DWI cases. The rules apply to any motorist charged after December 18, 2009, and convicted or pleading guilty after August 15, 2010. The new law does not apply to convictions of DWAI, which is a traffic infraction, but to all misdemeanor and felony DWI convictions.

This is the second part of a tough new state law (Leandra's Law) forcing anyone with a DWI conviction to get a device installed in their car which requires them to pass a breathalyzer test to start the engine. The device is referred to as an ignition interlock device (IID).

The law was named after 11-year-old Leandra Rosado, who died last October when the car she was in flipped over on the West Side Highway.

The first part of the law took effect in December, making it a felony for anyone to drive drunk with a child younger than 15 in their car. In the first six months, there were 248 Leandra's Law arrests across New York State. Drivers convicted under Leandra's Law, could face up to four years in prison.

Nine other states have laws requiring the IID to start the car, and many have shown declines in repeat offenses. According to proponent’s of the law, a study by the National Highway Transportation Safety Administration estimates that if interlock devices were more widely installed, they would save up to 750 lives a year.

The IID costs drivers about $170 to $200 for installation and $80 a month for maintenance. The device must be installed on every vehicle the DWI convict drives, adding to the costs.

Under Leandra's Law, judges can decide whether a DWI convict must also have a camera installed to record each test and a GPS device.

After the IID tests the driver at the start of the ride, it monitors them while on the road. An IID is similar to a breathalyzer, however an IID is connected to the vehicle dashboard or other location inside the vehicle and requires that a driver breathe into the device prior to starting the vehicle. If the ignition interlock device detects the blood alcohol concentration of the diver to be above the programmed limit in the IID, then the engine of the vehicle will not start.

Motorists who have a .025 blood alcohol content flunk, even though the legal threshold for drunken driving is .08 - because drivers with DWI convictions are not allowed a single drink before getting behind the wheel.