Reviewed and updated October 9, 2026 by the SearchSystems.net editorial team. The arrest counts are the ones each agency reported to the FBI, as the FBI held them on October 8, 2026. The jail figures are from the Vera Institute of Justice's Incarceration Trends data. Every office link was opened and checked against the office's own site on September 23, 2026.
Mercer County, Illinois, has about 15,000 residents (2024 Census Bureau estimate). A DUI arrest in Mercer County starts two cases, a criminal case in the Circuit Court of Mercer County and a license case before the Secretary of State, and leaves three records. This guide follows the arrest from the roadside to the court file and the driving record.
This guide covers the law, the arrest, booking, the court case, the license case, the records and common questions.
Related guides: Mercer County public records, Mercer County arrest records, Mercer County warrants, Mercer County inmate search, Mercer County criminal records, Illinois arrest records and Illinois inmate search.
The DUI Law in Illinois
In Illinois the offense is DUI, and the limit is 0.08.
Driving in Illinois is consent to a breath or blood test when an officer has cause to suspect DUI; the license case that follows a refusal or a failed test is run by the Secretary of State, separately from the criminal case.
Illinois sets no time limit on prior offenses: every earlier conviction counts toward a repeat charge.
Who Makes DUI Arrests in Mercer County
The Mercer County Sheriff's Office and the agencies that report for Aledo and Viola make the DUI arrests in Mercer County.
Aledo reported 34 arrests to the FBI for 2024, all offenses together; the FBI's count for Mercer County does not break DUI out.
The Alexis Police Department is listed by the FBI across two counties including Mercer County, so its arrests are not broken out for Mercer County here.
Booking After a DUI Arrest in Mercer County
A driver arrested for DUI and kept in custody goes to the county jail, whichever agency made the arrest. The jail, run by the Mercer County Sheriff's Office, held about 59 people on an average day in 2019 by the Vera Institute of Justice's count and has a jail page SearchSystems verified at mercercosheriff.org, phone (309) 582-5194. The Mercer County inmate search guide covers the jail in full.
The Court Case
The State's Attorney files the charge, and the case is heard in the Circuit Court of Mercer County.
The State's Attorney's page SearchSystems verified is at mercercountyil.org, phone (309) 582-5381.
The court records page SearchSystems verified for the county is at illinoiscourts.gov/courts-directory/104/Mercer-County-Courthouse/court, phone (309) 582-7122. That page belongs to a lower court, not to the Circuit Court of Mercer County.
Illinois has no single public index of every trial court case; each court's records are looked up through that court.
The License Case
A DUI arrest starts two cases: the criminal one above and an administrative one over the license, run by the Secretary of State. The driving record, kept by the Illinois Secretary of State, carries the result of both.
The Records a DUI Leaves
- The arrest report: from the agency that made the arrest, under the Illinois Freedom of Information Act.
- The court file: from the Circuit Court of Mercer County, kept by the Circuit Clerk.
- The driving record: from the Illinois Secretary of State.
More on each: Mercer County arrest records, Mercer County police reports and Mercer County court records.
Frequently Asked Questions
What is the DUI limit in Illinois?
0.08 percent blood alcohol.
Where is a DUI case from Mercer County heard?
In the Circuit Court of Mercer County, brought by the State's Attorney. The court records page SearchSystems verified for the county is at illinoiscourts.gov.
Where is a person arrested for DUI in Mercer County held?
At the county jail, run by the Mercer County Sheriff's Office, if kept in custody.
Who handles the license after a DUI arrest in Illinois?
The Secretary of State, in an administrative case separate from the court case.
How long does a DUI count as a prior in Illinois?
There is no time limit; every prior conviction counts.
Is this the official Mercer County website?
No. SearchSystems.net is an independent public records guide, online since 1997. It links to the official county, court and state offices described above and does not hold records, charge for them or take requests.