The United States Supreme Court decides cases involving the nation’s most pressing legal issues, affecting the daily lives of hundreds of millions of Americans — and yet so much about its functioning is shrouded in mystique and exclusivity. The court’s front doors are locked and its vast “public” plaza is off-limits to protesters. Alone among the branches of government, it refuses to televise its proceedings, even though its gallery can seat only 250 members of the public.

As a new report by Reuters shows, this exclusivity extends even to the types of cases the court agrees to hear.

The justices accept about 75 of the 10,000 petitions they get each year. And of that already minuscule fraction, a stunning proportion is argued by an extremely small and well-connected group of lawyers. All of these lawyers — among the top litigators in the country — have argued often before the court and almost all of them work mainly for corporate clients. Many have clerked for the justices, know them personally and socialize with them.

Those are the central findings of The Echo Chamber, a comprehensive analysis of about 10,300 petitions filed by private attorneys between 2004 and 2012. Reuters found that the lawyer’s name on the brief was among the strongest predictors of whether the justices would take a case.