In the State of Pennsylvania, much like other states, a person can not legally interpreter without being listed on the ODHH (Office of Deaf and Hard of Hearing.) While there may be a rare exception in the law, such as a serious medical emergency, it is a punishable offence. It not only puts the Hiring Agency at risk but the interpreter themselves. Below is a full list of acceptable ASL certifications.
To find out if your interpreter IS/WAS in fact certified- along with a list of certifications meanings, please see check: http://www.odhh.state.pa.us/Search/InterpreterSearch.aspx