Under the division of powers laid out in the U.S. Constitution, a topic like farm animal welfare clearly falls to the responsibility of the 50 states rather than the federal government. And on a practical level, that's fine.
Ballot initiatives and lawmakers in many of the states have sought to ban allegedly cruel practices, and such bans typically do not curtail the liberty of farmers or consumers in other states. They do, of course, tend to fragment a market that until lately was national — but neither consumers nor producers should necessarily object to that.
Unlike some other food products, meat is relatively well-suited to origin labeling, and the market is clearly developing in the direction of presenting diners and shoppers with explicit choices between fare produced under more animal-welfare-sensitive conditions — through certification or variation in state law — and that produced under more conventional factory farming methods.
The development of such markets will serve to inform the animal welfare debate in at least two ways. First, there's cost: will bacon and chicken breasts cost twice as much, or only modestly more, if pigs and chickens are more thoughtfully looked after?
With parallel mass markets in operation, we'll find out. And when humane-minded consumers confront that price tag, will they live up to their avowed beliefs? We'll find that out, too. A price system is a mirror, even if we don't always like what we see in it.