WASHINGTON -- The Supreme Court's august chamber was invaded yesterday by the northern spotted owl, the koala, rare turtles and the common crow. But it was in word only: Those creatures figured in two lawyers' sparring with the justices over endangered species.
In a case that one law professor has called "an epic dispute between private property and government regulation," the court focused on the power of the government to protect rare wildlife by punishing those who disturb nesting, breeding or feeding sites on public and private lands.
The dispute is the most significant one involving endangered species since the Supreme Court 17 years ago stopped a river dam project to protect the habitat of the snail darter fish.
But the new controversy emerges in a more heated political atmosphere, with the rise of a militant property-rights movement determined to scale back the government's environmental restrictions on private land use.
The intensity of the dispute showed clearly in the courtroom. The justices repeatedly rattled a Justice Department lawyer and a private attorney with tough questions on the meaning of a 1973 law, the Endangered Species Act.
At times, though, the justices also turned frivolous. Chief Justice William H. Rehnquist wondered aloud whether someone could be punished for going into his or her back yard and watching the birds, and upsetting them by doing so.
Justice Antonin Scalia teasingly sought to dissuade a colleague from talking about the koala: "Can you pick out an uglier creature? You pick out the cutest little critter."
When the case is decided later this spring, it could settle the fate of the timber industry's access to millions of acres of forest land in the Pacific Northwest, the habitat of two protected species: the northern spotted owl and the red-cockaded woodpecker.
The Fish and Wildlife Service, relying on regulations it has been enforcing for 19 years, has sought to protect the habitat of those two rare birds. Timber interests responded with a challenge to the rules, claiming that they go beyond anything ordered by Congress in the Endangered Species Act.
Under the regulations, it is a crime to modify or disturb the habitat of protected species in a way that threatens their existence. The regulations have been used by federal officials to encourage private property-owners to take action to protect the habitats of endangered creatures.
A federal appeals court struck down the regulations 13 months ago, saying Congress did not intend to make it a crime for private individuals to modify wildlife habitats.
All Congress wanted to do, the appeals court said, was stop private individuals from using force directly against protected animals. If the government wants to protect habitats, it has power to buy the land involved, the appeals court noted.
Deputy U.S. Solicitor General Edwin S. Kneedler urged the court yesterday to rule that it is as much a threat to a species to upset its habitat as it is to harm it directly.
John A. MacLeod, a Washington lawyer who is representing timber interests, argued that the government should be able to punish private individuals only for harms they do purposefully against wildlife.
Although Mr. Kneedler ran into aggressive questioning from Justice Scalia, Mr. MacLeod faced tough and skeptical questions from five of the nine justices.