Statement - I :One of the images in double refraction doesn’t obey the principles of refraction
Statement - II :Extraordinary image in double refraction doesn’t obey the principles of refraction because its velocity changes with direction.
 

Because the speed of light waves in a medium is equal to their speed in a vacuum divided by the index of refraction for that wavelength, an extra ordinary ray can be either faster or slower than an ordinary ray. The extra ordinary ray does not obey snell's law. It is because refractive index of the e-ray varies according to the direction taken because it has components that are both parallel and perpendicular to the crystal's optic axis.