## Facts

- Idaho’s livestock industry relied heavily on grazing on the federal public domain, which occurred with federal acquiescence and without federal regulation or fees.
- Idaho found that in arid regions extensive sheep grazing made ranges unsuitable for cattle, displaced cattle operations, and contributed to serious violence and loss of life.
- Because the state was sparsely settled and the public domain extensive, Idaho concluded effective policing of range conflicts was impracticable.
- Idaho enacted Rev. Codes § 6872 (1908), making it a misdemeanor for a person in charge of sheep to allow them to graze on a range previously occupied by cattle, with priority determined by “usual and customary” prior use as a cattle or sheep range.
- A sheep herdsman allowed sheep to graze on a range previously occupied by cattle, was convicted and fined, and the conviction was affirmed by Idaho appellate courts.
- The defendant sought review, arguing the statute violated the Fourteenth Amendment and conflicted with the federal Act of Feb. 25, 1885, restricting unlawful exclusive claims to public lands.

## Issues

1. Whether a state may, under its police power, regulate grazing on federal public lands when Congress has not enacted governing legislation.
2. Whether the statute violated the Fourteenth Amendment by abridging privileges of U.S. citizenship or denying equal protection by favoring cattle (and similar stock) over sheep.
3. Whether the statute denied due process because terms like “range” and “usual and customary use” were too indefinite for criminal enforcement.
4. Whether the statute conflicted with the federal Act of Feb. 25, 1885, prohibiting assertions of exclusive use and occupancy of public lands without valid title.

## Decision

- The Supreme Court unanimously affirmed the state judgment and upheld the conviction.
- The Court held the state’s police power may operate on the federal public domain when Congress has not legislated on the subject.
- The Court held the law was a reasonable measure aimed primarily at preserving the peace by segregating incompatible range uses.
- The Court rejected the Fourteenth Amendment challenges, finding no abridgment of federal citizenship privileges and no arbitrary discrimination under equal protection.
- The Court held the statute was sufficiently definite for criminal enforcement despite not specifying exact range boundaries or a fixed duration for “usual and customary” use.
- The Court held the statute did not conflict with the 1885 federal act because it did not grant exclusive rights; any exclusion of sheep was incidental to a police regulation.

## Legal Principles

- In the absence of controlling federal legislation, a state may apply police-power regulations to conduct on federal public lands to protect public order and local welfare.
- Grazing on federal public lands is not, without congressional grant, a federally secured privilege of citizenship; permissive use does not create a constitutional entitlement.
- A livestock classification tied to documented differences in range impact and to public-order objectives satisfies equal protection if not arbitrary.
- Criminal statutes using locally understood terms may satisfy due process when the terms have ascertainable meaning in context and under state-court construction.
- A state police regulation that incidentally limits certain uses of federal lands is not preempted by a federal statute aimed at preventing unlawful assertions of exclusive possession, absent an actual grant or assertion of exclusivity.

## Conclusion

The Court sustained Idaho’s cattle–sheep range segregation statute as a valid peace-preserving police regulation applicable on federal public lands where Congress had not regulated grazing, and it found no Fourteenth Amendment violation or conflict with the federal unlawful-occupancy statute.


Omaechevarria v. Idaho, 246 U.S. 343 (1918)