What is a Certified Legal Investigator (CLI)? What is required to become one? Private Investigators have a number of certifications available to them to increase their proficiency and standing in their chosen field of expertise. Some trade associations have strong certification programs and those with value often have daunting requirements, but are worth the work nevertheless. Author, teacher, and private investigator Rory McMahon will discuss certification programs, specifically one designed and administered by the National Association of Legal Investigators.