Here’s an interesting link: The History of Illinois DUI Laws, put together by the Illinois Secretary of State in 2003.
Interesting tidbits: From 1949 to 1953, a first offender would receive a mandatory minimum sentence of 10 days in jail. In 1953, it was reduced to two days. Currently, there is no mandatory minimum jail sentence, unless there is an aggravating factor.
The “legal limit” was 0.15 from 1958 until 1967, when it was reduced to 0.10. In 1997, it was reduced further to 0.08.
In 1967, the law was amended to add persons who were merely “in actual physical control of a motor vehicle” in addition to those who were driving.
A license suspension law called the “implied consent” law became effective in 1972. It called for a three month suspension for first offenders who refused or were unable to complete a test, or a six month suspension if they were a repeat offender.
More importantly, the law required two separate breath tests, to be done not less than 15 minutes apart. A second test is essential because it helps rule out error and confirm the accuracy of the test. The law also gave drivers 90 minutes to decide whether they wanted to take a test. Both provisions of this were removed in 1982, and now only one test is required, and police can order a person to make a decision much sooner than 90 minutes.
In 1985, the statutory summary suspension law went into effect, replacing the “implied consent” statute. It created, for first offenders, a three months suspension for failing a breath, blood or urine test, or a six month suspension for refusing or failing to complete. Second offenders received a one year suspension for either.
Nowadays, first offenders receive a six month suspension for failing a test, or a one year suspension for a refusal or failure to complete a test, and repeat offenders receive a one year suspension for failing the test or a three year suspension for refusing or being unable to complete a test.
As of 1961, a drunk driver was eligible to receive court supervision (a sentence which avoids a conviction and license revocation) every five years (I assume that prior to that, one could get supervision no matter what your background was, as long as a judge approved it). In 1993, this was changed to once every 10 years. I didn’t see it in the “History” but sometime around 1998 the law was changed again to allow only one DUI supervision in a lifetime.
The past 15 years have seen many changes to the law, including increased penalties for repeat offenses, for excessive BAC, and for DUIs with children in the vehicle. Other changes include lifetime revocation after four DUI convictions, and mandatory Breath Ignition Interlock Devices for first offender driving permits.