The Super Rich is the Am Law 100's most exclusive club. The entry requirements are formidably steep with firms having to demonstrate market-leading financial performance. This year, they've become even steeper.

Since the classification was first introduced in 2014, the membership criteria have remained the same. To get beyond the velvet rope, a firm has needed an average revenue per lawyer (RPL) of at least $1 million and average profit per equity partner (PPP) of at least $2 million. No mean feat. At least, it never used to be.

At first, just 20 firms made the grade. But thanks to gains in productivity and profitability across Big Law—and inflation—the group has gradually expanded, rising to 24 firms in 2015 and 28 last year.