The Interior Department’s on-again, off-again coal leasing program comes under the scrutiny of a federal appeals court March 23.

Environmentalists are suing to force Interior to perform a detailed study, known as a Programmatic Environmental Impact Statement, of the effects coal leasing has on climate change. If they prevail, the plaintiffs could stop the leasing program for years.

The immediate question before the U.S. Court of Appeals for the District of Columbia Circuit is whether a lower...