A method and an apparatus are disclosed for limiting the readability of optically-readable medium, wherein a combination of a liquid crystal material and a wavelength shifting material are incorporated into the optically-readable medium. The liquid crystal material is selected to substantially interfere with the reading beam of a reading device. The wavelength shifting material is selected to shift the wavelength at which the liquid crystal interferes with the reading beam so that the reading beam can read the optically-readable medium. A predetermined stimulus causes the liquid crystal material to shift back to a configuration that substantially interferes with the reading beam so that the reading beam can no longer read the content on the optically readable medium.