The arrest of a former Gibson Dunn & Crutcher visiting lawyer has put a spotlight on the role of “visiting attorney” arrangements in Big Law, why several large firms utilize the system, and the vetting that goes into employing such attorneys.

Romero Cabral Da Costa Neto was charged last week with insider trading. Costa, a former visiting attorney at Gibson Dunn from prominent Brazilian firm Mattos Filho, is accused of accessing internal law files through Gibson Dunn’s document management system to trade ahead of a major merger and acquisition.