Ignition Interlock Devices in Texas: What You Must Know
To Stay Out of Trouble
If a judge orders interlock, you must understand the rules to avoid violations and new charges.
What Is an Ignition Interlock Device?
An ignition interlock device (IID) is a breath alcohol-testing system installed in your vehicle that prevents the engine from starting if alcohol is detected. Courts use interlock devices to monitor drivers accused or convicted of alcohol-related offenses, especially DWI.
Montgomery County judges apply interlock requirements consistently with state statute. If your case is before a Conroe court or a precinct justice court in The Woodlands, Magnolia, or Willis, the judge will typically order interlock as a bond condition any time the charge alleges a second DWI or a first DWI with a BAC of .15 or higher. Courts in this county use an approved vendor list. Vendors near Conroe typically schedule installation within one to three business days. Your attorney can help you find a provider and confirm the court's current requirements before your first setting. If you have a bond condition that requires interlock, your compliance record is reviewed at every court date. Any logged violation will come up. The Law Office of Timothy Rose represents clients in Montgomery County on interlock violation hearings and bond modification requests.
When Is Interlock Required in Texas?
Under Texas Code of Criminal Procedure Art. 17.441, judges must require interlock as a condition of bond if the case alleges:
- Second DWI or more, or
- First DWI with a BAC of .15 or higher
Judges also have discretion to order interlock based on case circumstances — such as prior alcohol-related history.
How Interlock Violations Occur
Many people assume compliance is easy. But common technical issues become violations:
- Missed rolling retests (you must blow again while driving)
- False positives from mouthwash or acetone
- Power loss from battery disconnects
- Using someone else’s vehicle
Every action is logged. Courts and supervision officers review the data.
Can You Drive Without Interlock Installed?
No — not even once. If your bond or probation requires interlock, driving a vehicle without it is a new criminal offense and can lead to jail and revocation of bond.
Cost and Vendors
The court will typically provide a list of approved vendors. Costs vary, but drivers should expect:
- Installation: $70–$120
- Monthly fees: $60–$100
- Removal fee: $50–$100
If needed, we can request financial hardship adjustments.
When Can Interlock Be Removed?
Removal depends on the resolution of your case:
- Case dismissal or acquittal = removal request filed immediately
- Probation cases = specific compliance period must be completed
- Deferred cases = requirements vary by court orders
Your attorney should file paperwork — never have a vendor remove it without judicial approval.
How We Defend You Against Interlock Problems
If a violation report is filed, we focus on:
- Device inaccuracies
- Medical conditions (e.g., diabetes)
- Unauthorized data transmission
- Maintenance or power-related issues
Judges respond very differently when presented with clear technical documentation instead of excuses.
Don’t Let a Device Ruin Your Case
If you have interlock requirements or a violation issue — take action quickly.
Call now for guidance: (936) 777-4891