U.S. Citizenship and Immigration Services is issuing policy guidance to enhance the integrity of the review process for Form N-648, Medical Certification for Disability Exceptions. Under this guidance, USCIS is changing how we process Form N-648 by focusing greater attention on the veracity of medical certifications and identification and prevention of fraud, thereby enhancing the integrity of the process. Across the country and over the decades, there have been numerous instances where the medical certification process has been exploited.