Supreme Court veteran Carter Phillips of Sidley Austin remembers vividly the first time he offered a hiring bonus to a Supreme Court law clerk seeking a job at his firm. It was 1987, when bonuses were rare, and he tendered $10,000.

Thirty-one years later, the prevailing hiring bonus for Supreme Court clerks is $400,000—up from $300,000 in 2015. And that does not include salaries. If the trend continues, the clerk bonus will soon approach twice the annual salary of the justices they work for. Associate justices are paid $235,000, and the chief justice gets $267,000.