A major shift in New Jersey law took place earlier this month, but most state residents have not felt its effects. Those most likely to have felt its impact are those who have been pulled over by police, then arrested for driving while intoxicated and convicted of DWI/DUI.

The new law is something of a mixed bag for many of those drivers. The statute that took effect on Dec. 1 no longer requires driver’s license suspensions for most first offenders. While many will be relieved to know they can keep driving, they should be aware that the new law also requires all motorists convicted of drunk driving to install ignition interlock devices in their vehicles.

The devices are essentially Breathalyzers that must be used each time a person wants to drive. If the ignition interlock detects an unallowable level of alcohol in the driver’s breath, the vehicle will not start.

The devices are set to prevent use of the vehicle if it detects a BAC (blood alcohol content) of .05 percent or above. (It should be noted that New Jersey’s legal threshold for BAC is .08 percent.)

Some first DWI offenders will still be subject to driver’s license suspension, however. Those with a BAC of .15 percent could have their licenses suspended from four to six months. They can also be required to have the ignition interlock device in their vehicle for an extra nine to 15 months.

For those who are convicted a second time of drunk driving, they face up to a two-year license suspension as well as two to four years of mandated interlocks.

In case you’re wondering, yes, those ignition interlocks are installed and maintained in your vehicle at your expense. Installation is about $150 and then costs about $100 per month to lease and maintain.