I spoke with American Cruise Lines concerning the accessibility of American Constitution. Here is their reply:
All of our ships are handicap accessible and have elevators to each deck. All handicap staterooms are accessible including: Wider stateroom and bathroom doors for wheelchairs, grab rails around the bathroom, shower benches are available as well as raised toilet seats. There is a 5 ¾” lip going into the shower and onto the balcony. Wheelchairs cannot roll into the shower or onto the balcony. The majority of the shore excursions allow for wheelchairs and scooters and are handicap accessible. Guests who require the use of a wheelchair or a motorized scooter will need to bring their own from home or rent one from a medical equipment company to use while onboard.
This looks like a winner for any in the accessible community.