The Supreme Court could soon gut the ability of federal agencies to limit the pollution that creates smog and causes climate change.

This year, SCOTUS will weigh in on a pair of cases that could overturn or severely limit a foundational principal called Chevron deference. For decades, thanks to the Chevron doctrine, judges have deferred to experts at federal agencies on how to implement a law when there are disputes over interpreting language in legislation. Overturning that precedent would weaken the ability of the Environmental Protection Agency and other federal agencies to regulate industry.

In another high-profile case, SCOTUS will decide whether to stay the EPA’s Good Neighbor Plan. The plan is supposed to prevent smog-forming pollution from one state from drifting into other states. It’s a national strategy for reining in pollution that doesn’t stop at state borders. Around a dozen states are challenging the plan, however, and Ohio and other plaintiffs want the Supreme Court to pause the plan’s implementation while those cases make their way through lower courts.

The Verge has your guide to what’s at stake as SCOTUS considers key environmental lawsuits this year.