South Carolina DUI and Interlock Ignition Device (IID)


Today’s we are discussing the consequences of a DUI conviction and Interlock Ignition Requirements in South Carolina. You may be required to install an Interlock Ignition Device for two reasons: (1) A DUI/DUAC conviction or (2) A violation of the Implied Consent Statute and an Administrative Hearing.  We’ll focus on the interlock requirements for a DUI conviction today.

What is an Interlock Ignition Device?

A Interlock Ignition Device is a computer with a breath tube that analyzes the breath-alcohol concentration of a person. This computer is connected to the car’s computer ignition. The IID permits the car to drive. If the IID detects alcohol, it will shut off the car’s ignition. The purpose of the IID is to permit citizens to drive during the time their license would otherwise be suspended during a DUI.

When is an Interlock Ignition Device Required?

DUI 1st Offense when the BAC is a .15 or higher and DUI 2nd, DUI 3rd, and above.

(SC Code 56-5-2941 and 56-5-2990)

How Long is an Interlock Ignition Device Required?

            The short answer is the IID must be on the car for the same length as a suspension would have been.

DUI First Offense

6 Months

DUI Second Offense

2 Years (SC Code 56-5-2990)

DUI Third Offense

4 Years (If DUI 1st Offense was within 5 years) Otherwise 3 years

DUI Fourth Offense


Who Monitors my Interlock Ignition Device?

            Probation, Parole, and Pardon monitors the IID. When a person is ordered by the DMV to obtain an IID, they must report to PPP. PPP will then send the client to one of the three in-state vendors. These vendors will install the IID in your vehicle. PPP and the vendors monitor your IID for tampering and for compliance. PPP conducts a reading every 60 days on the IID to check compliance. More information can be found here.


If you’re arrested for DUI an IID may be a possible punishment. That’s why it’s important to consult with experienced DUI criminal defense attorneys. We at Cole Law Firm proactively and aggressively defend our clients. Contact us for a free consultation regarding your DUI or criminal case.