For professional services, English-ASL interpreters must be certified and qualified. Professional interpreting agencies have their procedures and they work closely with Deaf community.
Unfortunately, it happens often that hearing managers are ignorant of the qualifications when they come across hearing candidates who say they know sign language. Here is a few cases to start with the biggest one ever.
Thamsanqa Jantjie, a.k.a the fake sign language interpreter, appeared at the leader Mandela's worldwide-watched memeorial service, "interpreting" next to the global leaders for hours on December 10, 2013 in South Africa.
Deaf people, especially in the South Africa, immediately responded by tweeting around, in attempt to tell the officials to stop Jantjie and at least to get him off the stage immediately.
Even some Deaf people, who speak their own native signed languages but didn't know South African SL, could tell that Jantjie made gibberish, nonsensical, non-linguistic gestures. Yet, Jantjie still stood for hours alongside global leaders interpreting like a buffoon.
Hundreds of millions of people around the world watched Jantjie flapping hands around the speeches of Obama and other world leaders. Jantjie couldn't even translate the basic words such as "Nelson Mandela".
He grabbed worldwide headlines. How did he get this most prestigious interpreting position? It wasn't the first time. The South Africa government did NOT listen to its Deaf community prior to this worldwide spotlight.
This same guy had been interpreting for high-level speeches and conferences prior to Mandela which provoked many official complaints from the Deaf Federation of South Africa and Deaf activists, the South African government apparently ignored until the big moment which caused a massive embarrassment.
Jantjie was never a recognized professional interpreter in the country. “He is not known by the deaf community in South Africa nor by the South African Sign Language interpreters working in the field,” said a statement by the Deaf Federation of South Africa.
This raised some concerns from national security to ethics in sign language interpretation profession. There was clearly a loophole in security where world leaders made their presence at the memorial. Jantjie later was found that previously he was admittted to psychiatric hospital that he suffered schizophrenic episodes and heard angel voices.
In addition, he had a history of violent offenses. He was charged with a mob that burned a man to death in 2003 but he had never faced trial due to his mental unfit. He also had been charged with other offenses before that. Later, investigation found that a non-existing (or fake) interpreting service company who provided services to the government and paid the fake interpreter just disappeared.
This incident is the loudest reminder that underqualified or non-qualified interpretation in educational settings and such have happened and happened for some time.
For example, school administrators hire signers to "interpret" just because they know some sign language. Signed language is no easier than spoken language and it's not something to be taken lightly. It's as complex and natural as spoken language. Professional certified, trained interpreters are required for the positions in educational, legal, and such settings. Signers are simply not interpreters. Likewise, signers are not ASL instructors.
Another scenario: One morning I dropped my preschool to-be-bilingual ASL-speaking child at a ASL-English preschool, I noticed a new assistant who wasn't sociable nor interactive with me. Concerned for my child, I started talking with her like "Hello, how are you? What is your name?" to find out what her ASL skill is. Surprisingly, she wasn't able to make any conversation with me. For my child's safety, I brought this concern to the hearing signing director who said that the assistant had taken ASL 1, 2, 3, 4 at the (named) college. This sounds like a hugely impressive to her. As an ASL instructor at the university, I explained the director that at the community college (continuing education), the ASL 1, 2, 3, 4 series (not levels) are not only non-credit but also less-than-half equivalent to a credit-based ASL 101 course (four months course at a university). Did the director turn off English and converse in ASL with the assistant during their interview? No. From time to time, my second-year ASL level-200 students who asked for a volunteer work are referred to the preschool and deaf school. By the way, the misleading names ASL 1, ASL 2, etc. had been changed to now ASL Units 1 & 2 (based on the units of the textbook).
If you're a hearing employer looking for an applicant who adds their signing skills to their resume, don't take it at a face value if not relevant. Be familiar with sign language credentials if it's relevant.
If you're looking for an English/Spanish/French-ASL/LSQ interpreter as a staff (e.g. public schools or hospitals), contact professional sign language interpreting agancies and Deaf organizations for guidance or information. If you have Deaf employees, customers, or clients, they will choose interpreters or request to change them.
Listen to Deaf customers or clients if they bring up concerns about their experiences of the interpreting services.