Yes, this problem was raised recently in 2012 before the Federal/Provincial/Territorial Heads of Prosecutions Committee. The acuity of the problem depends on what region of Canada you live in. Indeed, in certain provinces such as the Prairies, British Columbia, Ontario and the Maritimes, the accreditation systems for interpreters in both official languages meet the demand quite well. A problem arises when it comes to other languages, however, we are not here to discuss that.
Unfortunately, accreditation of interpreters is not governed centrally according to national standards. As a general rule, we try to follow the program put into place by the Ontario Ministry of the Attorney General at the end of 1970s, which intended to train and accredit interpreters and ensure they maintained their accreditation in provinces where French was the minority language. Furthermore, very few complaints were made about this program.