In the past three months, the number of law firm mergers of U.S.-based firms has dropped, according to surveys by consulting companies Altman Weil and Thomson Reuters' Hildebrandt Institute.

Altman Weil said that in the first quarter of 2012, law firms reported 14 mergers, but the second quarter only saw 10. Hildebrandt's numbers differed—the company reported that there were only five mergers in the second quarter, compared to 20 in the first.

Altman Weil and Hildebrandt attribute the dropoff to several factors, including law firms focusing on strengthening local markets as well as the closely followed bankruptcy of Dewey & LeBoeuf, a firm that came to be as the result of a merger in 2007.