The law stating that in an X-ray diffraction pattern the intensity for a reflection associated with the Miller indices $\stackrel{}{hkl}$ is the same for a reflection associated with $\overline{hkl}$. This means that it is impossible to determine the chirality of a material using X-ray diffraction unless there is anomalous dispersion resulting in the breakdown of Friedel’s law. The law was stated by the French crystallographer Georges Friedel (1865–1933) in 1913.