Illinois breath tests are challenged on foundation under 625 ILCS 5/11-501.2 and the Illinois State Police administrative rules. Attack points include missing accuracy check logs, expired certification of the instrument, expired operator licensing, and gaps in the 20-minute observation period during which the subject cannot burp, vomit, or place anything in the mouth. Ambient contamination, residual mouth alcohol, GERD, and diabetic ketoacidosis produce falsely elevated readings. RFI from radios and cellular devices affects some machines. A Chicago DUI lawyer subpoenas maintenance records, operator certifications, and the source code documentation to build a suppression argument or a reasonable doubt trial defense.
