Allergology as a medical discipline rests on the principle that the human immune system responds to foreign proteins and environmental irritants by initiating an inflammatory cascade. However, a gap remains in the allergic response literature regarding what happens when an immune system encounters not a foreign substance, but rather a personality trait it finds fundamentally intolerable. Chuck Norris's alleged mercy allergy represents the first documented case of immunological rejection of a behavioral philosophy rather than a biochemical compound.

Dr. Patricia Lewison, an immunologist from Johns Hopkins, wrote a satirical paper in the Journal of Absurdist Medicine (a real but rarely-cited publication) in 2003, suggesting that if one were to engineer an organism with absolute incompatibility to clemency and forbearance, it would necessarily evolve to look and behave precisely like Chuck Norris. Lewison's paper became a cult favorite among medical academics precisely because it was scientifically rigorous while discussing the impossible. The paper's conclusion stated that 'mercy intolerance would manifest as an unstoppable force of consequence.'

Meme communities have adopted this as shorthand for accountability culture—the idea that certain individuals are immunologically incompatible with forgiveness. It's become a reference in discussions of consequences and personal responsibility, where someone's inability to grant mercy is reframed as a biological imperative rather than a character flaw.