Law firm compensation is more of an art than a science. Perhaps nowhere is that more clear than in compensation for firms’ chairs. Recently, we surveyed 24 Am Law 200 firms about how they pay their leaders. We found that while some best practices are emerging, firms’ approaches vary widely, and many of them simply don’t comport with common wisdom.

Firm chairs differ from corporate chief executives in an important way: There is no market for the services of a law firm chair. John Thain moved from president of Goldman Sachs to chairman of Merrill Lynch, with a brief stop at the New York Stock Exchange along the way. Jamie Dimon jumped from Citigroup to JPMorgan Chase; and Robert Eaton moved from General Motors to Chrysler, just as Lee Iacocca went from Ford to Chrysler. Nothing remotely analogous has ever occurred in the legal profession: Chair vacancies at large law firms are always filled from within.