Bibb v. Navajo Freight Lines, Inc., 359 U.S. 520 (1959), is a United States Supreme Court case in which the Court held that the Illinois law requiring trucks to have unique mudguards was unconstitutional under the Commerce clause.

If there are alternative ways of solving a problem, we do not sit to determine which of them is best suited to achieve a valid state objective.

Policy decisions are for the state legislature, absent federal entry into the field.

Unless we can conclude on the whole record that "the total effect of the law as a safety measure in reducing accidents and casualties is so slight or problematical as not to outweigh the national interest in keeping interstate commerce free from interferences which seriously impede it we must uphold the statute."

To find the statute unconstitutional, the Court balanced the benefit of the regulation to the state (in the form of increased safety) against the burden on interstate commerce arising from out of state truck drivers having to stop at the Illinois border and change mudguards.