WASHINGTON (AP) — The Obama administration is squaring off at the Supreme Court with industry groups and Republican-led states over a small but important program aimed at limiting power-plant and factory emissions of gases blamed for global warming.

The justices are hearing arguments today in a challenge to a regulation that forces companies that want to expand industrial facilities or build new ones that would increase overall pollution to evaluate ways to reduce the carbon they release. Carbon dioxide is the chief greenhouse gas.

The case comes to the court amid President Barack Obama's increasing use of his executive authority to act on environmental and other matters when Congress doesn't, or won't.

Opponents of the Environmental Protection Agency's program at issue at the high court call it a power grab of historic proportions.