Candidates may be excluded from a position if such a position requires substantial communication with customers and/or employees and the person’s accent is found to be strong enough to encumber their ability to communicate and would, hence, impair a person’s job performance.
This gets into a very scary area, however. One of the protected classes is that of race, and avoiding discrimination becomes a daunting task in today’s world.
Under these circumstances, good planning can certainly help with the review process. Requiring an oral language test that is well-scripted and given to all prospective candidates in the same fashion and environment would help avoid any possibility of crossing the line into discriminatory practice.
The more the focus is on “how a candidate could fulfill all of the elements as described in a job description”, the more companies can avoid any perception of bias.
In this instance, blind tests, where the tester can not see the candidate taking the test, would be a good practice as well.