The world of physics has a foundation built on beautiful universal constants, which work their way steadfastly into the equations governing electrodynamics, and then further extend themselves into our very hands in the design of smart interconnected electrical devices that are commonplace to modern life. Ironically, universal constants form the founda­tion of life for which it is popularly said that the only constant is change. This constancy of change is also very well proven in the world of medical device regulation, perhaps especially with respect to biocompatibility and how chemical information fits into that puzzle. Over the past 5 years, the medical device community has swung from nearly full ignorance of the poten­tial power of chemistry testing, to full adoration and acceptance, and now back – in a sense – to a state of scrutiny and skepticism. Regulators, in response to an influx of medical device submissions centered on supporting chemistry data, have increased their knowledge and finesse with the science and have been asking tough questions. Widely circulated studies have been critical of chemistry testing for toxicological evaluation of medical devices. Therefore, in response to this feedback, as medical device chemistry for toxicology (ChemTox) has matured, the overall strategy has changed dramatically on some points…