Leading attorneys in the U.S. are asking as much as $1,250 an hour, significantly more than in previous years, taking advantage of big clients' willingness to pay top dollar for certain types of services.

A few pioneers had raised their fees to more than $1,000 an hour about five years ago, at the peak of the economic boom. But after the recession hit, many of the rest of the industry's elite were hesitant, until recently, to charge more than $990 an hour.

While...