Your honor, the need for a CDI is unrelated to the skill level of the team interpreter. It is not possible for an interpreter who can hear to provide the same level of linguistic/cultural access that a Deaf interpreter can provide. A Deaf interpreter has the lived experience of being Deaf. To provide a comparison, suppose you are traveling to China. You have hired a tour guide who is an American but who majored in Asian Studies focusing on China. While you are traveling you are in an accident. Your tour guide is conversationally fluent in Mandarin, but is not familiar with medical terminology, the hospital system in China or the local dialects. Luckily he has a friend who is a professional. He calls his friend, and the two work together to help you get processed thru the medical system. The Chinese friend knows how the medical system works, what to expect, what to watch out for, etc. She knows the terminology the doctor is using and explains it to the tour guide, who then explains it to you in English. Since you now have both a person who knows the American healthcare system (what you know and expect) and the Chinese system (a system you do not know but now you must interact with) you feel less nervous about your care and treatment. The Chinese woman has a complete understanding of the healthcare system; how it works at the national/local level, how billing happens, etc. The situation requires someone who intimately knows the language and culture.
This is the role of the Deaf interpreter; to work alongside the hearing Interpreter and mediate between Deaf and hearing cultures so that the Deaf person has full access and understanding of whatever system they are interacting with; legal, medical, mental health, etc.
“Your honor, here we have a client who has a specialized culture and dialect. The NCIEC (National Consortium of Interpreter Education Centers) has produced research on the use of Certified Deaf Interpreters with this type of client as the most efficient and effective means of communication. With my 11 years of experience as a professional sign language interpreter, I have experienced great success working as a team with CDIs. Therefore, with the court’s permission, I would request a CDI team for any future assignments with this client.”