Originally Posted by
hubcap
I didn't know filtering was permitted in Illinois. Not that I doubt you, but do you happen to know what particular law allows that? I'd like to have it handy for future potential conflict resolution.

There is not a particular law stating it is legal, but there are no laws saying it is illegal. Therefore, it falls into the category of riders choice, and reasonable safety. I choose to filter, at least when I feel it's safe.
Here's a
link to the Illinois bike laws (subsection from the road laws).