In this article
A common misconception in U.S. legal and medical settings is that "sign language" is a single language. It is not. ASL (American Sign Language) is the dominant sign language of the U.S. Deaf community. LSM (Lengua de Señas Mexicana) is the dominant sign language of the Mexican Deaf community. They are mutually unintelligible to native signers without bridging interpretation. A Deaf client who immigrated from Mexico as an adult likely signs LSM. A Deaf client who grew up in the U.S. Deaf school system most likely signs ASL. Booking the wrong language is a communication failure.
How sign languages differ
Sign languages are not visual codes for spoken languages. They are full natural languages with their own grammars, vocabularies, and regional varieties. ASL and LSM are historically related (both trace back in part to French Sign Language) and share some signs and features, such as a manual alphabet and the use of facial expressions for grammar, but their vocabularies and grammars differ enough that the two are not mutually intelligible. A signer fluent in one cannot understand the other without learning it as a separate language.
How to know which sign language your client uses
- Where did the client learn to sign? Country of origin and age at immigration are strong indicators. A client who emigrated from Mexico as a child and attended U.S. schools likely signs ASL. A client who emigrated as an adult likely signs LSM.
- What Deaf community does the client belong to? Members of the U.S. Deaf community generally sign ASL. Members of the Mexican Deaf community in Mexico or in U.S. enclaves often sign LSM.
- If you are scheduling for a court matter and have any doubt, ask the client (through a hearing relative or written communication) before booking. AMS can coordinate a quick written confirmation.
- Some Deaf clients are bilingual in ASL and LSM. In that case, ask which language the client prefers for the proceeding.
What happens when the wrong language is booked
The Deaf client cannot understand the interpretation. The interpreter cannot understand the client. The proceeding stalls. In a legal matter, the proceeding may have to be continued and rescheduled with the correct interpreter. In a medical setting, the clinical encounter becomes ineffective. In both, the cost of the error is significantly higher than the small effort to confirm the right language upfront.
Other sign languages occasionally requested
In addition to ASL and LSM, AMS occasionally fills requests for British Sign Language (BSL), International Sign (IS, used in conferences), and bridging interpretation through a Certified Deaf Interpreter (CDI). For clients who use foreign sign languages other than LSM, a CDI working with a hearing interpreter is often the right configuration; see our Certified Deaf Interpreter article for the longer explanation.
How AMS handles this at scheduling
When scheduling sign language interpretation, the AMS dispatcher asks about the client's country of origin, age at immigration, and signing background. If there is any doubt, we coordinate a quick pre-call with the client or family to confirm the right language. We supply RID-certified ASL interpreters and qualified LSM interpreters in all 50 states, on-site and by video.