Facts of the Case

Arizona banned operation of trains more than 14 passenger cars of 70 freight cars long.

Question

Was the Arizona law an unconstitutional burden on interstate commerce?

Conclusion

Yes it was such a burden. The Arizona law imposed a stiff burden on the railroad. It had to operate 30 percent more trains in the state, and it had to break up and remake trains passing through the state. The total cost was several million dollars a year. Moreover, more trains would produce more accidents and the state's safety argument was empirically weak. The innovation in this decision was Stone's use of an "interest-balancing" standard of review, which proved more demanding than the earlier "rational basis" test.