The U.S. Supreme Court's October argument calendar has already been described as containing one of the most consequential batch of cases in awhile.

But it also may be known as the calendar that shuffled the plans of more advocates than any other time in recent memory.

Take Hogan Lovells partner Neal Katyal, who was hoping to argue Monday in the trio of major cases that will decide the fate of class action waivers in employee arbitration clauses. He represented Murphy Oil in National Labor Relations Board v. Murphy Oil.

But Williams & Connolly partner Kannon Shanmugam, who wrote the brief for Ernst & Young in Ernst & Young v. Morris, also wanted that argument slot. For undisclosed reasons, neither Katyal nor Shanmugam got it. Instead the prize went to Kirkland & Ellis partner Paul Clement, who had no prior involvement in the cases.

If anyone can jump into a complex argument at the eleventh hour, Clement—known for arguing without notes—is the lawyer who can do it. But he too had some scheduling issues. He was already scheduled to argue on October 11 in Jesner v. Arab Bank, the closely-watched Alien Tort Statute case.

But in addition to that, on September 25, the court issued an order granting argument time to Wisconsin state legislators in the key gerrymandering case Gill v. Whitford. Clement, a Wisconsin native, filed the brief on behalf of the legislators, so he could have chalked up a third argument for October. But in the end, Clement's longtime colleague Erin Murphy stepped in to argue in his stead.

Back to Katyal. The arbitration case was not the only October argument Katyal was prepping for. He was also scheduled to argue on October 10 against the Trump administration's travel ban, a cause he felt passionate about: Trump v. Hawaii and Trump v. International Refugee Assistance Program.

But when the solicitor general's office alerted the court that a new travel plan was in place, the justices on September 25 yanked the cases from the argument docket, pending further briefing about mootness.

So Katyal went from two October arguments down to zero, a development that was particularly unfortunate because his next Supreme Court argument will be a milestone. The late Thurgood Marshall—who was sworn in as a justice exactly 50 years ago today —argued 32 times before the high court, and so has Katyal. With his next argument, Katyal will surpass Marshall as the minority lawyer with the most arguments at the Supreme Court. Katyal was born in Chicago of Indian parents.

“It will be December now” when he surpasses Marshall, Katyal said in an interview. That is when Katyal will argue in Cyan v. Beaver County Employees Retirement Fund, a securities class action case.

How did Katyal feel about crossing the October arguments off his to-do list? “Obviously there was some disappointment,” he said, but added, “I've not had a weekend off since November of last year.”

The cancellation of the travel ban arguments also delayed newly confirmed solicitor general Noel Francisco's debut in that capacity.

Francisco had been expected argue in the October cycle, but the court's decision to delete the travel ban case came too late for him and other staff to switch gears. But other recent newcomers to the office—Erica Ross, Jonathan Ellis, Chris Michel, Frederick Liu and Michael Huston—are also not making their debuts at the high court this cycle.

One private-practice lawyer who is arguing at the high court this week for the first time is Jessica Amunson, partner in Jenner & Block's appellate and Supreme Court practice and chair of the firm's election law and redistricting practice.

On Tuesday, Amunson will be “second-chair” to former Jenner partner Paul Smith, who will be arguing in the Gill v. Whitford gerrymandering case. The next day, Amunson will argue on her own for the plaintiff in Class v. United States, a criminal procedure case that has not gotten much attention, even though it poses an important question: whether a defendant who pleads guilty can still try to invalidate his or her conviction by claiming that the statute of conviction is unconstitutional.

“Our moot courtroom here at Jenner & Block has gotten a lot of use over the past couple of weeks,” Amunson said in an interview. “It has been very helpful in preparing for my first argument at the court to have the assistance and insight of my many Jenner colleagues who have already been through this experience themselves.”