GWEN IFILL:

The Supreme Court today ruled against Amazon warehouse workers who argued that they should be paid for the extra time it takes them to be screened at the end of the workday.

Cases like this are often argued by a relatively tight circle of lawyers who are well-known to the justices and are more likely to share the same education and private firm pedigrees.

Reuters looked at 17,000 petitions filed with the court to try to put numbers to that conclusion, and uncovered an unusually insular legal world at work at the nation's top court.

Reuters legal editor Joan Biskupic joins us to detail the findings.

Joan, start by telling us, exactly what does it take to become a lawyer who argues at the court?

JOAN BISKUPIC, Legal Affairs Editor in Charge, Reuters: Well, you can be admitted to the Supreme Court bar just by virtue of being a lawyer anywhere out in the country.

But for this tight group, it's these repeat performers, they're people who have come up mostly as perhaps Supreme Court law clerks themselves, worked behind the scenes, worked for the prestigious Office of the Solicitor General. Those are the people who are dominating now.

But, generally speaking, anyone who's a lawyer who's admitted to the Supreme Court bar, which literally would cover thousands, tens of thousands out in America, can argue. It's just that we have found is that, more and more, clients are turning to this select group. And the justices themselves seem to be signaling that they're interested not just in the merits of a case that is presented to them, but the merits of the lawyering, just because of what the data have shown.