State troopers say they pulled over a pickup truck on Interstate 70 near Troy because the driver improperly changed lanes.
Illinois State Police investigators say they were involved in separate crimes.
The new law allows trucks to go 65 on four-lane divided highways that are not interstates.
The move comes one week after the ACLU filed a complaint with the U.S. Department of Justice.
ACLU says Illinois state police pull-over and search Hispanic drivers differently.