It allows Illinois residents to possess 30 grams of cannabis, 5 grams of cannabis concentrate and 500 milligrams of THC contained in cannabis-infused products. Visitors from other states could possess half of those amounts. SPRINGFIELD — A 532-page proposal to legalize adult-use cannabis in Illinois by Jan. 1, 2020, was filed in the state Senate on Monday, but the powerful speaker of the Illinois House said its passage is "not guaranteed today." read more