The world's top-grossing law firms didn't just cross the $100 billion revenue threshold for the first time in 2017—they vaulted across it.

Total revenue for the Global 100 increased a robust 6.4 percent in 2017, dwarfing rises of 2.8 percent and 3.1 percent from each of the previous two years. These firms brought in a collective $105.7 billion dollars, almost $10 billion more than the 2015 total. And a total of 41 firms cracked the $1 billion mark, up from 34 firms in 2016.

"It's reflective of the fact that last year was the first in a long time that most firms had all practice areas faring well," says former Clifford Chance managing partner Tony Williams, now a management consultant at Jomati.