Is a right-handed negative refracting material possible ?

The notions left-handedness and negative refraction are closely related because every left-handed material should show negative refraction. However, there exist no left-handed materials in nature and artificially produced left-handed materials, which exist up to now only for microwaves, suffer from several limitations. Therefore, we investigate under which circumstances a right-handed material refracts negatively. Conditions for the dispersion relation and the dielectric function of a right-handed negative refracting material are derived. It is checked whether these conditions are compatible with the Kramers-Kronig relations. Thereby, it turns out that the conditions can only be fulfilled in an active medium.