All certified interpreters are required to follow the RID Code of Ethics which can be found
here. This Code of Ethics requires that interpreters behave in a manner appropriate to their position, e.g. interpreters may not add to, omit, or change the message they are interpreting; all assignment-related information must remain confidential; interpreters will use their judgment when accepting assignments; no personal opinions or advice can be interjected while interpreting. If you feel an interpreter has behaved unethically, you can contact RID/BEI to find out how to file a grievance against that interpreter
here or
here.