49 CFR §39.45

1. (a)As a PVO, you must not subject passengers with a disability to restrictions that do not apply to other passengers, except as otherwise explicitly permitted in this part.
2. (b)Restrictions you must not impose on passengers with a disability include, but are not limited to, the following:
   1. (1)Restricting passengers' movement within the vessel or a terminal;
   2. (2)Requiring passengers to remain in a holding area or other location in order to receive transportation or services;
   3. (3)[Reserved]
   4. (4)Requiring passengers to wear badges or other special identification; or
   5. (5)Requiring ambulatory passengers, including but not limited to blind or visually impaired passengers, to use a wheelchair or other mobility device in order to receive assistance required by this Part or otherwise offered to the passenger.
3. (c)Special muster stations for disabled individuals are permissible for emergency evacuations in order to centrally locate available resources.