Section of statute is 625 ILCS 5/11-701

Applicable text:

(d) Upon an Interstate highway or fully access controlled freeway, a vehicle may not be driven in the left lane, except when overtaking and passing another vehicle.

(e) Subsection (d) of this Section does not apply:
(1) when no other vehicle is directly behind the vehicle in the left lane;
(2) when traffic conditions and congestion make it impractical to drive in the right lane;
(3) when snow and other inclement weather conditions make it necessary to drive in the left lane;
(4) when obstructions or hazards exist in the right lane;
(5) when a vehicle changes lanes to comply with Sections 11-907 and 11-908 of this Code [625 ILCS 5/11-907 and625 ILCS 5/11-908];
(6) when, because of highway design, a vehicle must be driven in the left lane when preparing to exit;
(7) on toll highways when necessary to use I-Pass, and on toll and other highways when driving in the left lane is required to comply with an official traffic control device....

So there are exceptions which will help folks wriggle off the rap. #1, which applies if no one is behind you, is the main one. But if you've ever been ticketed in the boonies or in some state outside your own you know that does you little good. Feel like driving 500 miles for a court appearance to argue the case?

Until Jan. 1 of this year the law simply forbid going too slow for "normal traffic" in the left lane.

All I'm reporting is that tickets for improper lane usage in the first 3 mos. of this year have doubled and tripled, compared to last year. State and local governments are strapped for $$$ and traffic ticketing (like parking fines) is being used as a backdoor tax.