When I looked up french websites and blogs on advice regarding to the adequate space in the run for backyard hens the numbers were much, much larger, between 100 and 200 sq ft per chicken.The current woefully inadequate allowance for a run is ten square foot per bird
Prison turn people crazy, it's not humane. Also, it's not illegal to have a family of fifteen live in a 50 M2 flat and it's fairly inhumane. What it leads to is inadequate behavior. However I and many chicken keepers don't necessarily know what would be adequate chicken behaviour. I learnt a lot about it on this thread. I wouldn't have been able before reading all this to tell if my chickens were displaying disturbing behaviour for chickens. I know a little better by now but wouldn't feel experienced enough to say if they are happy or just adapting.Should one of us be unfortunate enough to get sent to prison under most civilised regimes we would be entitled to an hour of exercise away from our cells. So, one hour a day minimum would seem humane. Lets go with this as a starting point.
It's not just the extra room, it's some relief from the boredom and monotony of living with the same surroundings day in day out. Bored chickens are not well or happy chickens in my experience.
Years ago I kept a cat in a flat with no access to the outdoor and I honestly believed she was happy. Now we have two cats in what really is the ideal environment for them and it completely changed my mind.