John Leffler is an experienced testifying expert and peer-reviewed author with over 1,000 forensic cases of experience, including 550+ product cases and 400+ cases involving premises liability and pedestrian falls. An ex-IndyCar mechanic & fabricator, John ran a product design engineering firm for eight years after working for five years designing machines, consumer products, and commercial products for several manufacturers. A 1993 graduate of Georgia Tech, John also taught product design materials and manufacturing processes at GT's College of Design for fifteen years. For over 17 years, John has been heavily involved in standards development within ASTM International and several other ANSI-accredited organizations. Because following a standard is the "standard of care" in many situations, he worked in leadership roles in these organizations in order to understand the applicability and relevance of standards and to improve their technical foundations. The primary author of ASTM E2713 (forensic engineering) and both ASTM F2948 and F3539 (pedestrian walkway safety), John is a nationally recognized leader in standards development across five different organizations and is the Chair of ASTM subcommittees on bathing surfaces and on walkway friction. In 2021 John initiated and led a groundbreaking and Federally-funded research project in support of replacing the obsolete ASTM standard for bathing surface friction. John has also manufactured research-proven walkway friction test "tribometers" since 2010, and the devices are used by insurance companies, theme parks, research labs, and forensic professionals around the world.