Be careful. If their ability to speak and understand English is essential to doing the job, this is a reasonable criterion to use. But you would have to demonstrate conclusively that a certain standard of English is required; and you would also have to demonstrate that you are applying exactly the same criterion to workers who are native English speakers. If you attempt to get non-native speakers to take a test while native speakers are excused, you lay yourself wide open to a charge of race discrimination (see Discrimination).
