
What to Know About Ignition Interlock Devices in California
Ignition interlock devices (IIDs) are essentially miniature breathalyzers specifically calibrated to prevent motorists from driving while intoxicated. IIDs are now a common penalty for driving under the influence in California.
How Do Ignition Interlock Devices Work in California?
As aforementioned, an IID is a tool used to measure a person’s blood alcohol content (BAC) — essentially a mini-breathalyzer. It is about the size of a cellular phone and is electrically wired into a vehicle’s ignition system. In the event that a judge orders you to install an IID as part of probation, it must be professionally installed into every vehicle you own or drive.
In order to start your car, you must blow into the IID. Then, this device will measure your BAC to determine if you are sober enough to safely drive. If the device reads that your BAC exceeds the limit, it will lock down for a few minutes before you can try again. A longer lockout will ensue for subsequent attempts.
If your breath sample is free of alcohol, the car will start. Once driving, you will have to submit to “rolling" samples. Rolling samples simply mean that after five to fifteen minutes while on the road, the IID prompts you to provide another breath sample. The IID will continue to request new samples every 45 minutes or so thereafter until you stop driving.
To note, if you are uncomfortable providing a sample while driving, you have six minutes to provide the sample. Feel free to pull over at your earliest availability so you can timely blow into the device.
Also to note, if any of your “rolling" samples fail due to the detection of alcohol, the car will still operate. The IID will, however, immediately log the sample as a fail and report the result to the court.
Mechanisms in Place to Ensure You Alone Provide the Breath Sample
Requiring periodic rolling samples is one way IIDs ensure you are the only one providing breath samples. There are other ways IIDs guarantee motorists are not gaming the system. They include:
- the cord used is short and cannot reach the passenger seat or back seats;
- the motorist must submit samples according to a certain breath pattern; and
- it is a crime to have someone else blow a sample for you.
Is It Unlawful to Bypass or Tamper With an Iid in California?
The IID is governed by Vehicle Code 23247. According to Vehicle Code 23247(b), it is against the law to ask or solicit someone else to provide a breath sample in your place.
It is also a crime to tamper (Vehicle Code 23247(d)) with the device or try to remove it. California IIDs are so technologically advanced that they will detect and record any instance where an individual tries to disconnect or deactivate the device.

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Case Dismissed Client Charged With Theft And Elder Fraud
IIDs and False Positives
Although it is pretty rare to get a false positive IID result, it definitely does happen. All technology is prone to fail at one point or another, so it’s no surprise that an IID may produce a negative result even though the driver has not consumed any alcohol.
Here are a few reasonable explanations that can cause a false positive:
- Mouthwash: Mouthwash contains considerable levels of alcohol. This is why experts suggest people with IIDs wait at least 15 minutes to submit a sample after using mouthwash for the substance to dissipate.
- Spicy foods: Spicy food mixed with hydrochloric acid, a compound found in the stomach, creates methane. At high levels, this gas can lead to a false positive.
- Energy drinks: Lots of energy drinks contain low concentrations of ethanol.
Don’t fret. If you “fail” an initial IID test due to any of the reasons listed above, you will be given an opportunity to retest almost immediately. Rinse your mouth out and wait a few minutes before retesting.
