Southern Pac. Co. v. State of Arizona Ex Rel. Sullivan, Attorney General of Arizona
Headline: Court strikes down Arizona train-length law, blocking state limits that forced extra trains and added costs while protecting national rail uniformity and interstate commerce.
Holding: The Court held that Arizona’s law limiting interstate trains to fourteen passenger cars and seventy freight cars unconstitutionally burdened interstate commerce and could not be enforced.
- Blocks states from enforcing differing train-length limits that disrupt interstate rail service.
- Protects national rail uniformity and prevents added costs from breaking up long trains.
- Leaves safety standard changes to Congress or the federal rail regulator.
Summary
Background
A state official sued a major railroad for operating interstate trains inside Arizona that exceeded the state’s 1912 limits of fourteen passenger cars and seventy freight cars. The railroad admitted the operations and argued the law conflicted with the Constitution and federal regulation. A trial court ruled for the railroad, the Arizona Supreme Court reversed, and the case reached this Court.
Reasoning
The Court examined whether Congress or the Interstate Commerce Commission had already displaced state control and whether the Arizona safety law unreasonably burdened interstate commerce. It held that the Commission’s broad authority did not by itself supersede state laws absent specific administrative action. The Court accepted factual findings that long trains were standard nationwide, that Arizona traffic was overwhelmingly interstate, that the law forced about 30% more trains in Arizona and raised operating costs by roughly $1,000,000 annually, and that the law disrupted efficient, uniform movement. The trial record also showed the length limit did not clearly improve safety and might increase other types of accidents. Balancing safety against national needs, the Court concluded the safety benefit was slight or doubtful and the burden on interstate commerce substantial, so the state law could not stand.
Real world impact
The ruling prevents single states from imposing differing train-length caps that break up interstate trains, raise costs, and impede efficient national rail service. It leaves decisions about uniform train-length rules and related safety standards to Congress or the federal regulator. The Supreme Court reversed Arizona’s enforcement for the 1940 violations at issue.
Dissents or concurrances
Two Justices dissented, arguing courts should not overturn a state safety law adopted by the legislature and voters and that the record showed genuine safety concerns; one Justice simply concurred in the result.
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