Even law firms rooted in the 19th and early 20th centuries—and steeped in traditional practices—have become leaders on the latest trends in intellectual property law, fiercely battling a decidedly 21st century development, patent trolls. We received dozens of nominations for our annual list of the hottest IP firms, and after extensive research concluded the 20 listed below deserved the accolade. Many rank among the most venerable in the country. Apparently that’s no bar to life on the cutting edge.