True, if you get a life sentence in Denmark you will most like be free quicker than someone getting fixed sentence for somewhere between 12 - 18 years.
It should be noted that that if you kill a police office and get a life sentence, the you will stay in prison for a VERY long time.
Police officers > Citizens
Well no, that's not really the point, at least in Denmark. A murder is a murder regardless of the victim, but the murder/attack on a police officer is an attack on the state (The police being the organisation through which the government exercises power, in some areas).
What happens if one hits a flower pot on the balcony with their elbow and it falls on a police officer's head... attack on the state or not?
That's hardly a murder, no?
That is not true. If you get 12 to 18 years, you can get parole after 6 to 9 years. The earlies you can get out with a life sentence is 12 years.