THE ISSUE: The Supreme Court hears arguments Tuesday in two Michigan cases that will help determine which wetlands are subject to regulation under the Clean Water Act.

THE ARGUMENTS: Environmentalists say virtually all wetlands should be covered. Property-rights advocates say the law protects only wetlands directly adjoining navigable waterways.

WHY IT MATTERS: Wetlands act as filters, removing contaminants that otherwise would pollute lakes and rivers. They store floodwaters and provide wildlife habitat. But protecting them limits what property owners can do with their land.

By The Associated Press