As a 100% disabled veteran with Multiple Sclerosis, incontinence, and restless sleeping problems I can tell you a crib has sure helped me. And yes there are serious legal problems that can be associated with restricting an adult. In my case I fall out of bed alot while sleeping and I live alone.
Physical restraints do have to be prescribed!! The restraints must also be able to be released easily by caregiver in event of emergency. In the case of living alone the restraints now not only have to restraint but be able to be releasable by the patient in event of emergency.
In my case VA provided a hospital bed with the standard hospital rails that pull up. The bed railings do prevent falling out of most patients. Problem in my case hospital railings were horizontal!!@ When I got restless at night I would get caught up in the railing and dislocate a shoulder, leg, or hip. After this happened a few times the VA ordered a crib from Hard Mfg in NY ( http://www.hardmfg.com/ ). The crib has vertical railings like your normal baby crib and does prevent my fall outs. The company can also custom make to fit most situation. The crib works fine and is very easy to open by the adult care giver by simply squeezing the railing release on the bottom of the railing. For the patient that lives alone reaching the release is a bit trickier but can be done by reaching through the railings or the release can be ordered & installed on the inside. To prevent the patient from reaching the release crib bumpers can be ordered. The bumpers are 1" thick 12 - 14" high. A mesh netting could also be used.
The crib looks like a stainless steel animal cage but it does work. I no longer have the crib (I didn't like sleeping in a steel cage). But I had a friend custom build a wooden crib out of Black Walnut. The new crib is a Twin XXL size with the same function as the one provided by the VA. I am 6'1" tall and easily fit this crib and the railings extend to about 5' over the top of the mattress. When the railing is up I could certainly say nobody is easily ever going to get out of it. The railing also goes to un extended position just at 14" above the mattress and it bumpers.
My friend build the crib I currently have and it is heirloom quality in both material and workmanship. He build and sold it to me for $1,000. If you buy one from a manufacturer such as Hard, Simmons, or other be prepared for the sticker shock as the start at $3,900