Found this to be interesting, right from the fmcsa itself...
CSA - Frequently Asked Questions now what I'm wondering is if a driver refuses the test wswhat grounds they can disqualify you on..they would have no evidence of sleep apnea and they can't disqualify you on your bmi or neck size...it would be a question for a good lawyer. I'm still taking my sleep test but I have also contacted the aclu here in Baltimore (not that it will do any good, but who knows) to see if maybe this could be considered discrimination...