The Supreme Court just put a crucial part of Obama’s climate plan on hold

The Supreme Court has just put a kink in President Obama's global warming agenda. How big a kink, though, remains to be seen.

In a surprise 5-4 decision on Tuesday evening, the justices halted implementation of the EPA's Clean Power Plan — a sweeping regulation to cut carbon-dioxide emissions from US power plants — until the legal challenges to the rule have been resolved.

Some background: The Obama administration finalized the Clean Power Plan last summer. The rule will basically require every state to submit a plan between 2016 and 2018 for reducing CO2 emissions in their electricity sectors by a certain amount. These state plans would then have to take effect by 2022 at the latest, and states would have a lot of flexibility in deciding how to cut: more efficiency, more renewables, switching from coal to gas, trading, whatever they choose.

This regulation was supposed to be the centerpiece of President Obama's broader climate agenda. At the international talks in Paris last December, the United States pledged to cut overall greenhouse gas emissions at least 26 percent below 2005 levels by 2025. It's virtually impossible to meet that promise without the Clean Power Plan.

Yet as soon as the Clean Power Plan was finalized, it was challenged by 26 states, led by West Virginia and Texas, who called it "the most far-reaching and burdensome rule EPA has ever forced onto the states." You can read up on their legal challenges here — one key question is whether the Clean Air Act gives the EPA authority to regulate CO2 in this fashion. These states also asked the courts to suspend implementation of the rule (known as a "stay") until there was a final ruling.

Initially, the courts sided with Obama on this. On January 21, a three-judge panel of the DC Circuit Court — the appeals court below the Supreme Court — agreed to hear the legal challenges but refused to issue a stay in the meantime. Oral arguments for that case start June 2. (Two of the judges were appointed by Clinton and Obama, so it seems plausible that the DC Circuit will ultimately uphold the plan.)

Now, however, the Supreme Court has stepped in and said, no, no, let's suspend implementation of this rule until the courts figure out if they'll uphold the Clean Power Plan or overturn it. That means the DC Circuit Court will have hear and rule on the legal challenges this summer, and (presumably) the Supreme Court will decide whether the rule stands or not. Only then can the EPA go forward with implementation.

So what does this mean in practice? A few early thoughts:

1) This isn't a fatal blow for Obama's climate rule, though it's not a great sign. It suggests that five justices on the Supreme Court have some doubts about the Clean Power Plan. (The justices who voted in favor of the stay were Roberts, Alito, Scalia, Thomas, and Kennedy.)

2) Many states will presumably continue thinking through how they'll implement the Clean Power Plan regardless. Otherwise, they run the risk that the Supreme Court will uphold the regulation and they'll have to scramble to submit a plan by 2016 (or by 2018 if they ask for an extension).

3) If the Supreme Court does ultimately uphold the law, this stay might not have much practical impact in the end. The Clean Power Plan doesn't require CO2 cuts until 2020-2022, by which point all this litigation will will presumably have been resolved.

4) It's a good reminder that the Supreme Court is extremely important for all manner of policy, and the next president will likely have a say in picking a justice or two.

Further reading: How the Clean Power Plan actually works, a step-by-step guide