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.

Dewey’s demise resulted in a mass exodus of many of its partners, who moved their practices to other high-profile firms. Winston & Strawn brought on 60 lawyers from Dewey and Greenberg Traurig, which was at one time in merger talks with the failing firm, hired at least 50 of Dewey’s lawyers. 

Some U.S. mergers, of course, did go through in the second quarter. Those included Frost Brown Todd merging with the small Nashville, Tenn., law firm MGLAW, as well as Buchanan Ingersoll & Rooney merging with fellow-Pittsburgh firm Manion McDonough & Luca.

Outside of the U.S., there’s another merger that’s garnering some attention. Yesterday, London-based Herbert Smith and Freehills, an Australian law firm, announced their merger. The joint venture will create a 2,800 lawyer firm called Herbert Smith Freehills, which will have 20 offices around the world. When that merger is complete on Oct. 1, it will be the eighth largest law firm worldwide, and will have one of the largest legal presences in the quickly growing Asia-Pacific market.