Someone who is arrested for Driving Under the Influence (DUI) may have questions about how long the DUI can be used against him. This issue can arise in several contexts but should not be confused with similar but different situations.
A statute of limitations as a defense to a DUI charge is limited to one specific situation. The state (police and or prosecutor) must, in charging any criminal offense, including DUI, allege in a written instrument the date of the claimed offense.
The charging instrument may be in the form of a traffic ticket (known as a complaint) issued by a police officer. The state may alternatively make the charge by bringing an "information", a document filed by or on behalf of the state's attorney. Or the charge may come through a grand jury indictment.
In all cases, the charge must be filed with the circuit clerk within a limited period of time after the incident date alleged in the information, indictment or complaint. For a misdemeanor DUI, that time period, which is known at the statute of limitations, is 18 moths. For a felony, it is 3 years. 720 ILCS 5/3-5
If a charge is filed within the above time frames, the statute of limitations is no longer a defense available to the accused (defendant). There may or may not be other defenses but not the statute of limitations.
Perhaps a charge is filed against you but takes a long time to resolve. Here the applicable time limit is the speedy trial act. 725 ILCS 5/103-5 In Illinois state court, if you are in custody (jail) and file a proper speedy trial demand, you must be brought to trial within 120 days. If you are not in custody, the state has 160 days to bring you to trial.
The tricky part of what seems like simple math is that any delay in bringing the defendant to trial that is attributable to the defendant does not count. So if you fail to show up for your trial date and the case is set to a later date, that delay does not count towards the speedy trial time. Or if you or your lawyer requests a continuance, or if you and the state agree to continue the case, the delay counts against you, not the state.
If the state requires a continuance, the delay counts in your favor, although if the state can present good cause for the delay (such as a witness that suddenly becomes unavailable), the judge may give additional time. People v. Exson, 896 N.E.2d 844, 384 Ill. App.3d 794 (1st Dist. 2008) A delay that works against the state is if the court system is not prepared, such as no available judges or jurors or courtrooms.