---
title: "What are the grounds for suppressing evidence in an Illinois DUI case?"
description: "Evidence suppression in an Illinois DUI case rests on constitutional and statutory grounds. The most common suppression targets are the traffic stop itself (no reasonable articulable suspicion under..."
url: https://chicagoduilawyer.net/faq-items/what-are-the-grounds-for-suppressing-evidence-in-an-illinois-dui-case/
date: 2026-07-08
modified: 2026-07-08
author: "Chicago DUI Lawyer"
type: faq
lang: en
---

# What are the grounds for suppressing evidence in an Illinois DUI case?

Evidence suppression in an Illinois DUI case rests on constitutional and statutory grounds. The most common suppression targets are the **traffic stop itself** (no reasonable articulable suspicion under the Fourth Amendment), the **arrest** (no probable cause to believe DUI occurred), **field sobriety test administration** (failure to follow NHTSA standardized protocols), and the **breath, blood, or urine test** (violations of 20 IL Admin Code 1286 covering machine calibration, officer certification, and the 20-minute observation period). Miranda violations can also suppress post-arrest statements, though field questioning before formal arrest is not Miranda-protected in Illinois. A successful motion to suppress the arrest typically ends the criminal case because there is no admissible evidence left to prove DUI.