No it's legal because driving is a privilege not a right. The Bar is working on legislation to remove the lifetime ban but it meets with a lot of resistance. I am on the legislative subcommmitte and we hope to try again this spring.
No there is no such thing as an 18 month suspension. So whatever you think you heard is wrong. And Illinois does not have a DMV. The Secretary of State administers drivers' licenses. And the DMV does not have mediators, they are called hearing officers. Suspensions are for 6 months 12 months or 3 years. A three year suspension does not entitle you to a hardship license. You cannot even have a hearing if you have a three year suspension.