It's true and David Kelley, the writer and producer, knows whereof he speaks. A couple of years ago, when this show was called The Practice (from which Boston Legal spun off), he had a series character (Rebecca) who turned out to be an inactive dub whose JW mother insisted she not have a blood transfusion when she either had an accident and/or needed surgery (can't remember the details). The writers got that right, too.
There must be an ex-dub on the writing staff over at The Practice/Boston Legal.