## Facts

- A county weights-and-measures director enforced California rules requiring that the average net weight of sampled lots of prepackaged goods at the time of sale not be less than the labeled net weight.
- California implemented the requirement through statistical sampling that tolerated manufacturing variation but made no allowance for weight loss from moisture evaporation during ordinary distribution.
- After sampling lots of prepackaged bacon and flour offered for sale, the director found average lot weights below labeled weights, largely due to moisture loss, and ordered the packages removed from sale.
- The producers sought declaratory and injunctive relief in federal court, claiming federal law preempted California’s scheme.
- Federal labeling regimes for meat and packaged foods required accurate net-weight statements while permitting reasonable variations, including moisture loss during good distribution practices.
- The producers contended California’s no-moisture-allowance rule effectively forced overfilling or packaging changes despite compliance with federal standards.

## Issues

1. Whether California’s net-weight requirements for bacon were expressly preempted by the Federal Meat Inspection Act because they imposed marking/labeling/packaging requirements “in addition to, or different than” federal requirements.
2. Whether California’s net-weight requirements for flour were preempted by federal food-labeling law, including whether the scheme conflicted with federal objectives of uniform net-weight standards and thus was invalid under obstacle preemption.

## Decision

- The Supreme Court affirmed the judgment for the producers.
- As applied to bacon, California’s statute and implementing regulations were preempted because they were “different than” federal requirements by disallowing moisture-loss variations that federal rules expressly permit.
- As applied to flour, California’s statute and regulations were preempted because they conflicted with the federal scheme’s objective of nationally uniform net-weight labeling and comparability, making state enforcement an obstacle to congressional purposes.

## Legal Principles

- Express preemption applies when Congress prohibits state marking, labeling, or packaging requirements that add to or differ from federal requirements; a state standard is preempted if it removes federally permitted tolerances that are part of the federal rule.
- Conflict preemption includes “obstacle” preemption: a state law is invalid if it stands as an obstacle to the accomplishment and execution of Congress’s full purposes and objectives, even if compliance with both state and federal law is not strictly impossible.
- Where federal labeling rules allow reasonable net-weight variations (including moisture-related changes during normal distribution), a state may not enforce a net-weight regime that effectively requires different labeling or packaging outcomes by refusing to recognize those variations.
- Congressional objectives in federal packaging and labeling regulation include uniformity and enabling fair consumer comparisons across jurisdictions; inconsistent state technical standards that defeat uniformity are preempted.

## Conclusion

The Court held California could not enforce net-weight rules that treated moisture-loss variation as unlawful when federal labeling regimes for meat and packaged foods permit such reasonable variation, because the state scheme imposed different requirements for bacon and obstructed national uniformity goals for flour.


Jones v. Rath Packing Co., 430 U.S. 519 (1977)