Are Radar Detectors Legal in Illinois? Detectors, Jammers, Trucks and Mounts

Last reviewed: October 18, 2026. This article is general information, not legal advice. We read some Illinois statutes in reproductions (an archived copy of the Illinois General Assembly page and FindLaw) because the Assembly's site was unavailable to us, so check the official text for recent changes.

Illinois is a good example of why "radar detector" and "radar jammer" aren't the same thing in the eyes of the law. Illinois leaves detectors alone in ordinary cars, but it has its own statute banning radar and laser jammers. If you drive in Chicago traffic, commute on I-55, or haul freight across the state, here's what the rules actually say. For other states, see our guide to where radar detectors are legal.

Short answer: yes, radar detectors are legal in Illinois in private passenger vehicles. Illinois has no statute banning them in ordinary cars. Radar and laser jammers are illegal under 625 ILCS 5/12-613, and detectors are banned in commercial motor vehicles because Illinois adopts the federal rule. Mount a detector where it doesn't materially obstruct your view.

Private cars: detectors are legal

We found no Illinois statute that bans owning or using a radar detector in a private passenger vehicle. That covers cars, SUVs, pickups and vans you drive for personal use, whether you live in Illinois or are passing through.

A detector only listens for police radar (and, on many models, laser) and warns you. That's the key legal difference from a jammer, which actively sends out a signal. Illinois's jammer statute is written around devices "designed to interfere", and a passive detector doesn't do that.

A detector still doesn't change the speed limit or stop an officer from pacing you, and Illinois work zones and school zones are enforced the same way whether or not you have one.

Radar and laser jammers: banned under 12-613

Illinois is one of the states that bans laser jammers by name, not just radar jammers. Here's how 625 ILCS 5/12-613 works:

• What's banned (subsection a). Operating, or being in actual physical control of, a motor vehicle equipped with any instrument designed to interfere with microwaves or lasers at police radar frequencies used to monitor speed.
• The storage exception (subsection b). You aren't in violation if the jammer is "contained in a locked opaque box or similar container, or that is not in the passenger compartment of the vehicle, and that is not in operation."
• The penalty (subsection c). A petty offense, with a minimum fine of $50 for a first offense and $100 for a second or later offense.
• Seizure (subsection d). The officer must seize the device at the time of the violation. It isn't permanently forfeited, but to get it back you must petition the court and prove by a preponderance of the evidence that it "will be used only for a legitimate and lawful purpose."
• No stop on that basis alone (subsection e). An officer may not stop or search a vehicle or driver "solely on the basis of a violation or suspected violation of this Section."

Radar jammers are also illegal under federal law, which bars willful or malicious interference with licensed or government radio communications (47 U.S.C. § 333).

Commercial trucks and buses: no detectors

Illinois adopts the Federal Motor Carrier Safety Regulations by reference. Under 625 ILCS 5/18b-105(b), several parts of Title 49 of the Code of Federal Regulations, including "Part 392--Driving of Motor Vehicles", are "hereby adopted by reference as though they were set out in full." Part 392 contains the detector ban in § 392.71.

What that means for you:

• Possession is enough. A CMV that is "equipped with or contains" a detector breaks the rule, even if it's unplugged.
• Carriers are responsible too. Under § 392.71(b), a motor carrier may not "require or permit" a violation.
• The CMV definition is broad. Under 49 CFR § 390.5, it generally includes a vehicle rated at 10,001 pounds or more, one designed or used to carry more than 8 passengers (including the driver) for pay or more than 15 not for pay, or one carrying placarded hazardous materials.
• "Radar detector" is broad too. Section 390.5 covers devices that detect radio microwaves, laser beams "or any other future speed measurement technology". A device is excluded only if it's carried outside the driver's compartment and is completely inaccessible to, inoperable by and imperceptible to the driver while driving.

If you drive a delivery truck, shuttle bus or heavy work truck and trailer, leave the detector in your personal car.

Windshield mounting under 12-503

Illinois's windshield statute has two parts that matter for a detector:

• Subsection (a) bans signs, posters and similar material on the front windshield, with exceptions such as a nonreflective tinted strip that extends no more than 6 inches down from the top.
• Subsection (c-5) bans objects "placed or suspended between the driver and the front windshield which materially obstruct the driver's view." It adds that no vehicle, driver or passenger "shall be stopped or searched by any law enforcement officer solely on the basis of a violation or suspected violation of this subsection."

So an obstructing mount is a secondary issue in Illinois, but it can be added to a ticket if you're stopped for something else. Keep the detector low on the glass or on the dash, out of your line of sight, and tidy the power cord.

A quick comparison

The FCC rule behind detectors

The FCC regulates radar detectors as unintentional radiators under Part 15. Since 2002, 47 CFR § 15.109(h) has required that "Radar detectors shall comply with the emission limits in paragraph (a) of this section over the frequency range of 11.7-12.2 GHz." The FCC adopted the rule after finding that detectors were leaking strong signals into the band used by small satellite (VSAT) terminals. Its 2002 order also noted that manufacturers had raised oscillator frequencies partly to make detectors harder for police to detect. Buying an FCC-certified detector keeps you within federal equipment rules, but it doesn't make a jammer legal.

Military bases and Washington, D.C.

• Military bases. Illinois installations such as Naval Station Great Lakes and Scott Air Force Base set their own traffic rules. Federal rules for Army installations (32 CFR § 634.25) note that Defense Department policy delegates authority to installation commanders to set additional traffic rules, and detectors are widely reported to be banned on bases. We could not open a single federal rule that bans them on every base, so check before you drive on.
• Washington, D.C. The District bans selling detectors and using or possessing one in a car (18 DCMR § 736). Driving east through Virginia, a detector must be unpowered and out of reach.

Driving to Michigan or New York? See our guides for Michigan and New York. If you're also checking other Illinois rules, see is pepper spray legal in Illinois.

Sources

• 625 ILCS 5/12-613 (radar or laser jamming devices prohibited): Illinois General Assembly; copy read at FindLaw
• 625 ILCS 5/18b-105 (adoption of Federal Motor Carrier Safety Regulations): Illinois General Assembly; copy read at FindLaw
• 625 ILCS 5/12-503 (windshields must be unobstructed): Illinois General Assembly (read via an Internet Archive copy)
• 49 CFR § 392.71 (radar detectors in commercial motor vehicles): Cornell LII
• 49 CFR § 390.5 (definitions): Cornell LII
• 47 U.S.C. § 333 (willful or malicious interference): Cornell LII
• 47 CFR § 15.109 (radiated emission limits, including radar detectors): eCFR
• FCC, Radar Detectors final rule, 67 FR 48993 (July 29, 2002): GovInfo
• 32 CFR § 634.25 (installation traffic codes): Cornell LII
• District of Columbia Municipal Regulations, 18 DCMR § 736: DC Regulations