The scariest words this month don’t come on Halloween. They cme on the first Monday of October: “The Supreme Court is back in session.” Be afraid; be very afraid.

The Supreme Court has two quite different dockets. There is the emergency docket, sometimes called the shadow docket, where the Court acts quickly without full briefing or oral argument. Then, without giving an opinion, it determines whether some sort of temporary (i.e., emergency) action should be taken.

Then there is the docket often called the merits docket, the one I will focus on here. These cases have written arguments by the litigants (briefs) followed by oral arguments and written opinions explaining the decisions of the Justices. Cases on the merits come before the Supreme Court when four Justices of the Court agree to hear them.  A writ of certiorari (which, I believe, is Latin for “Bring it on”) is granted. More colloquially, the Court grants “cert.” Right now 30 cases have been granted cert.  This is less than half of the cases usually decided in a term, so the Court will continue to add cases in the coming months. Oral arguments for cases on the merits docket started this week.

Many of the cases now docketed are technical in nature and will garner little attention from most of us. Several cases, however, are potentially noteworthy and of general interest. One of those cases asks whether there a Second Amendment right to possess an AR-15 or a similar semiautomatic weapon? These guns are sometimes called assault rifles.

Several cases will consider whether religious freedom is being infringed, including whether local land use regulations can prevent the construction of a religious structure on property that a religious institution owns. Another religion case involves the provision by Colorado of money to both public and private (including religious) pre-K schools, but only if those schools do not discriminate on sexual and gender identity grounds. The defendant (a Catholic Church) is asking the court to force Colorado to carve out an exemption for it so it can continue to discriminate on these grounds and still get the taxpayer money. The Church is arguing that it is religious discrimination against the Church if such an exemption is not granted.

The Court will hear several immigration cases. One deals with immigrants who have been granted asylum status but whose asylum was later terminated. Can they still become lawful permanent residents or are they categorially barred from permanent status? Another immigration case asks under what circumstances, if any, may the government deport people to countries where they have no contacts or ties? A third case: When, if ever, does the government have to give a bail or bond hearing to a detained undocumented immigrant?

The list goes on.

An important parental rights case: Can parents challenge a state law that displaces parental determinations on “gender transitions”?

Voting. Does federal law prevent Arizona from requiring “satisfactory evidence” of citizenship to register to vote and whether federal law prevents Arizona from purging noncitizens from registrations within 90 days of an election?

The case, however, with the widest potential impact is Suncor Energy v. County Commissioners of Boulder County, which was argued this week. Colorado localities have sued the oil companies Suncor and Exxon Mobil under state law for the harm greenhouse gas emissions have caused to the global climate. Suncor is arguing that federal law and the Constitution prevent this use of state law. At first glance, this seems like a normal contention that comes up often, i.e., When does federal law preempt state law? But in the usual preemption situation, there is a federal law that contradicts, or conflicts, or is inconsistent with a state law, and the question is whether under such circumstances the state law can still be enforced. This case, however, is different. There is no specific federal law that is at odds with what Boulder is doing. Instead, Suncor’s novel argument goes along these lines: Since greenhouse gas emissions cross interstate and international boundaries, a state can act against the oil companies only if Congress has affirmatively authorized state action since the Constitution gives Congress the power to regulate interstate commerce. That concept is new.

A decision on the merits, of course, will greatly affect oil companies. There are fifty or more suits around the country similar to the Colorado one. The companies argue that billions upon billions of dollars are at stake, and the companies could be bankrupted because of such suits.

Something more general is also at stake. If the Court accepts that the states cannot act because Congress has not authorized state action, this decision will mean that other companies will begin to look for similar situations where states, lacking specific congressional authorization, are prohibited from acting. In other words, what other circumstances would be like climate where states cannot act?

However, there are also technical jurisdictional issues in this case. Normally, the Supreme Court does not decide a case until that litigation has had a final determination in the lower court. That is not the situation here. Although the case has gone on for years, it some ways it is just at the beginning. The Colorado Supreme Court has ruled only that the suit can proceed to its next stage. It has not, in fact, been fully litigated in the lower court. The U.S. Supreme Court case might be decided on the procedural issues and not the merits.

And there is another kicker here. In a rare move for the Court, Justice Samuel Alito has recused himself from this case. No reason is given, but it is assumed it is because he owns oil company stocks, and all oil companies will be affected by the outcome.

It’s going to be an interesting term. Boo!