The coordinated settlement agreement that lifted a legal cloud over Airbus was the product of an extraordinary, multiyear collaboration among five top-tier law firms in three countries, working closely with Airbus and national authorities in a “virtual law firm” whose size and scope was unprecedented, according to lawyers involved.

Airbus will pay a total of 3.6 billion ($4 billion) to authorities in France, the U.K. and the United States to settle a four-year-long investigation into accusations that the aerospace giant, based in Toulouse, France, arranged bribes to sell its products between 2004 and 2016 in violation of International Traffic in Arms Regulations (ITAR).