WASHINGTON – The always-hot legal market for U.S. Supreme Court law clerks has gotten even hotter for those who served at the high court last term. Hiring bonuses have reached $300,000.

The new milestone, first reported by Above the Law, underscores the growing allure of high court clerks among big law firms seeking hard-working associates with cachet—the exclusivity of being one of only 39 lawyers privy to the inner workings of the court. (Each sitting justice has four clerks, while the three retired justices get one clerk each.) Added to first-year associate salaries, the bonuses can mean earnings of close to $500,000 during the former clerk's first year.

Interestingly, New York law firms have become increasingly willing to pony up the large bonuses. This year's list of firms paying $300,000 includes New York giants Paul, Weiss, Rifkind, Wharton & Garrison; Skadden, Arps, Slate, Meagher & Flom; and Sullivan & Cromwell.

Traditionally, New York firms have not fielded big Supreme Court practices, because the return is not as high as with other practice areas. "It's not particularly profitable for a New York firm interested in high-end practices," said one New York partner who declined to be quoted by name.

Their increasing willingness to pay high hiring bonuses to clerks does not necessarily mean the New York firms are changing their minds and building Supreme Court practices. It's just that they are ready to pay top dollar for top-drawer associates who can help the firm in any arena.

"In today's market, there is an increasing competition to attract the best talent," said Brad Karp of Paul Weiss. "Supreme Court law clerks are a very good bet in that regard."

Paul Weiss lawyers have argued only occasionally before the Supreme Court over the years, although its latest at-bat was a big one: the same-sex marriage case U.S. v. Windsor, a win for partner Roberta Kaplan. It is also notable that all three women on the Supreme Court—Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan—were once summer associates at Paul Weiss.

At other firms, the $300,000 milestone has not seemed to attract the grumbling that accompanied past increases. "It's a good investment," said Lisa Blatt, who leads the Arnold & Porter appellate and Supreme Court practice. Some veteran advocates used to complain that high court clerk hires would work a few years to pay off student debt, then depart for academia or government work.

"We already have made offers with that bonus number in them and we have one acceptance so far," said Carter Phillips, chairman of Sidley Austin's executive committee. Phillips said he and partner Peter Keisler were recently recalling some of the former clerks Sidley has hired, and "how extraordinarily well they are doing. So if you find the few who really want to practice law, the investment is well worth every penny. But the practice from the '80s and early '90s of corralling as many as you can get and hope that one or two will stay forever is not an attractive course to follow at this price tag."

Thomas Dupree Jr., hiring partner in the D.C. office of Gibson, Dunn & Crutcher, agreed the clerks are worth the money.

"Supreme Court clerks are talented young men and women who are very much in demand by the nation's top law firms," Dupree said in an email. "We view the bonus as a long-term investment in the clerk's career with Gibson Dunn, and we have been very successful over the years in hiring the best and the brightest young lawyers as our associates."