Richard Chandler Jr., executive vice president, chief legal officer and secretary of Chicago Bridge & Iron Co., turned to Wachtell, Lipton, Rosen & Katz to negotiate a definitive agreement for the engineering and construction company to acquire The Shaw Group Inc. for about $3 billion.

Shaw Group, based in Baton Rouge, La., is using lawyers from Vinson & Elkins of Houston and Jones, Walker, Waechter, Piotevent, Carrere & Denegre of New Orleans in the deal that was announced on July 30.