The Panama Papers Leak brought forth a list of individuals who had paid Mossack Fonseca, a law firm headquartered in tax haven Panama, and bought the benefits of the secretive, lax regulatory system in which it functions to set up offshore entities in tax havens around the world. Mossack Fonseca, a law firm headquartered in tax haven Panama, and bought the benefits of the secretive, lax regulatory system in which it functions to set up offshore entities in tax havens around the world.