Jerome Friedman and Valentine Telegdi, at the University of Chicago, test Lee and Yang's suggestion that the weak interaction might not conserve parity. They study the decay chain of positive pions through muons to positrons (π⁺→μ⁺→e⁺), measuring in nuclear emulsion the angular correlation between the muon's flight direction and the positron's emission direction. Across 2,000 complete events they detect a clear forward-backward asymmetry, confirming parity violation at both stages of the process. The result is received by Physical Review on January 17, 1957, the same week the results of Chien-Shiung Wu's cobalt-60 experiment and the parallel Garwin-Lederman-Weinrich experiment on the same π-μ system using a different method are announced: the three experiments, carried out independently and almost simultaneously, together confirm Lee and Yang's theoretical prediction and force abandonment of the previously unquestioned assumption that parity is conserved in all fundamental interactions. The finding is one of the experimental pillars on which the electroweak theory of the Standard Model would later be built.