In the 1800s, Indian tribes (plaintiffs) ceded roughly the northern third of Wisconsin to the United States under treaties reserving the tribes’ right to hunt there. Wisconsin tribes relied on hunting deer and used it in cultural and religious traditions. The tribes preferred hunting at night, when deer freeze in bright lights, making them easy targets. Wisconsin (defendant) eventually outlawed night hunting, except on reservations comprising a tiny percentage of the ceded lands, and a federal judgment upheld the law in 1991. During the late 1990s, the state began shooting deer at night to control the exploding population and eliminate endemic disease. Despite using state employees and contractors with little experience or training, the rate of hunting accidents in Wisconsin plummeted. Collisions between motor vehicles and deer caused far more fatalities and injuries. Over a five-year period, hunting accidents injured only four nonhunters, and most hunter injuries were self-inflicted. The tribes brought a federal action against the state to overturn the 1991 judgment as obsolete, arguing that the state’s more recent experience with night hunting proved it was safer than previously thought. By that time, neighboring states had allowed night hunting in ceded territories similar to Wisconsin’s for over a decade and required night-hunting safety courses managed by the Great Lakes Indian Fish and Wildlife Commission, which also oversees hunting in Wisconsin. The tribes demonstrated outstanding hunting safety records on tribal reservations where night hunting was allowed. The trial court nonetheless upheld the 1991 judgment, reasoning that state employees and contractors hunting deer at night was less dangerous than allowing tribe members to do so. The tribes appealed.