Bacteria react to injury, they remember the past, and they even predict the future. If you buy into the theory that causing pain is immoral then every cow is a walking Auschwitz. (not even to mention the problem of brushing teeth)
By the way, there is no philosophical reason why "it feels pain" is a better standard for deciding whether injuring something is cruel than any other arbitrary standard, see Hume
Even the ATF isn't stupid enough to try to ban peeing without a license.
What makes you think that?? They've ruled that shoelaces are machine guns, ruling that pee is an explosive would be a return to common sense by their standards
Understanding is always the understanding of a smaller problem in relation to a bigger problem. -- P.D. Ouspensky