WASHINGTON—Prominent insurance attorney Charles Landgraf has joined Arnold & Porter L.L.P., the most recent in a series of high-profile insurance attorneys to exit financially ailing Dewey & LeBoeuf L.L.P.

In addition to Mr. Landgraf's departure, the Pension Benefit Guarantee Corp. sued Dewey & LeBoeuf last week to force the New York-based law firm to turn over its three pension plans to the agency and appoint it the plans' trustee; the landlord of the firm's New York office, Property Group Partners, reportedly sued the law firm over more than $900,000 in unpaid rent; and layoffs had reduced the law firm's staff to 100 employees from 533, according to the New York State Department of Labor.

Mr. Landgraf's departed as chair of Dewey & LeBoeuf's legislative and public policy practice group and as managing partner of its Washington office to join Arnold & Porter as a partner in its Washington office.

Since early March, defections mounted as Dewey & LeBoeuf struggled financially. Six insurance lawyers, including captive industry expert P. Bruce Wright, joined New York-based Sutherland Asbill & Brennan L.L.P., while 12 insurance attorneys joined New York-based Willkie Farr & Gallagher L.L.P.

James R. Woods, co-chair of Dewey & LeBoeuf's global insurance industry practice, joined Mayer Brown in New York. In addition, four lawyers led by John Nonna, chair of Dewey & LeBoeuf's insurance and reinsurance dispute resolution practice, joined Patton Boggs L.L.P. in New York in early April.

In its announcement, Arnold & Porter noted that Mr. Landgraf has represented leading companies and trade associations in the insurance industry, including Lloyd's of London, the California Earthquake Authority and Liberty Mutual Insurance Co.

“Mr. Landgraf's work on behalf of insurance-sector clients has included the formation of Policyholders Benefit Corp. to assume undefaulted insurance obligations when the then-largest” private mortgage insurer was put into liquidation during the savings and loan crisis, Arnold & Porter said in the statement. “Mr. Landgraf also played a key role in representing clients in the development and passage of the Terrorism Risk Insurance Act of 2002, the successful efforts to renew the TRIA program in 2005 and 2007, and the development of insurance measures in the Dodd-Frank Act.”