It is shown that prolongation of patent protection for the antiviral drug darunavir by patenting it again as darunavir ethanolate is illegal. The claims of the successor patent “Pseudopolymorphic forms of a HIV protease inhibitor,” WO 2003106461 A2, are analyzed and shown to be invalid from both scientific and ethical viewpoints. It is established that darunavir was initially used as its ethanolate. Darunavir is one of the best protease inhibitors of both types of HIV. Currently, not only darunavir ethanolate but also amorphous darunavir (unsolvated) are used as active pharmaceutical ingredients with INN darunavir. This was confirmed by x-ray diffraction studies. Justification for the orderly invalidation of this patent in the RF was given.