Bibb v. Navajo Freight Lines, Inc.,
359 U.S. 520 (1959)

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U.S. Supreme Court

Bibb v. Navajo Freight Lines, Inc., 359 U.S. 520 (1959)

Bibb v. Navajo Freight Lines, Inc.

No. 94

Argued March 30-31, 1959

Decided May 25, 1959

359 U.S. 520


As applied to interstate motor carriers operating under certificates of public convenience and necessity issued by the Interstate Commerce Commission, the Illinois statute here involved which requires trucks and trailers operating on that State's highways to be equipped with a specified type of rear fender mudguard which would be illegal in Arkansas, which is different from those permitted in at least 45 other States, and which would seriously interfere with the "interline" operations of motor carriers, is invalid because it unduly and unreasonably burdens interstate commerce in violation of Art. I, § 8 of the Constitution. Pp. 359 U. S. 521-530.

(a) Even state safety regulations must yield when they run afoul of the policy of free trade reflected in the Commerce Clause. Pp. 359 U. S. 523-524, 359 U. S. 528-529.

(b) Interchanging mudguards on trucks and trailers at the border of Illinois is a time-consuming task, and the necessity to use welding might mean that some trucks or trailers would have to be unloaded and loaded again -- all of which adds up to a serious burden on interstate commerce not justified by a compelling need for this new safety measure. Pp. 359 U. S. 527-528.

(c) The record in this case shows that this is one of those exceptional cases where a state safety regulation in the exercise of the police power places such a heavy burden on interstate commerce, uncompensated by compelling advantages of safety, that it violates the Commerce Clause. Pp. 359 U. S. 529-530.

159 F.Supp. 385, affirmed.

Page 359 U. S. 521

Primary Holding

The government cannot enact a safety statute that burdens interstate commerce much more than it benefits local commerce, even if the law is facially neutral.


Illinois required that trucks and trailers on its highways use a contoured mudguard, while Arkansas required them to have a straight mudguard. All of the other states required one type or the other. Arguing that the Illinois law unduly burdened interstate commerce, Navajo Freight Lines, Inc. prevailed in the lower court, which issued an injunction preventing Bibb from enforcing the law.



  • William Orville Douglas (Author)
  • Earl Warren
  • Felix Frankfurter
  • Hugo Lafayette Black
  • Tom C. Clark
  • Charles Evans Whittaker
  • William Joseph Brennan, Jr.

A strong presumption of validity attaches to state safety statutes regarding highways because a significant state interest is implicated. However, this law would create substantial additional costs for carriers because every truck traveling across state lines would need to have this specific type of mudguards, since it would be difficult to determine when a certain truck would enter Illinois. Trucks that traveled across both Arkansas and Illinois would need to either avoid a state or change their mudguards at the border. Further complications would arise when trailers were interchanged among carriers.

No clear benefits of using contoured mudguards could be identified, and they might even lead to additional hazards. As a result, the presumption of validity may be overcome because the burdens on interstate commerce are so heavy.


  • John Marshall Harlan II (Author)
  • Potter Stewart

Case Commentary

The statute placed a substantial burden on major trucking companies because it would not allow them to shift cargo among lines if the mud flaps did not meet the state's requirements. This issue and others imposed logistical complications and costs on the companies, which the court found to outweigh the state interest in regulating its highways under the dormant Commerce Clause.

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