Some might argue that because they put their life on the line to protect people, they hold more value. But in that case you could argue that a doctor who saves lives is more valuable than a cop.
So why don't you get a mandatory life sentence if you kill a doctor? Why are cops so special? I mean, they're still just a person, just as someone who isn't a cop is a person.
I'm not implying cops are *less* significant. Here's what I think should happen:
Punishment severity depends on crime severity. You shoot someone in cold blood: 20 years. You torture them for several days before shooting them: Life sentence.
Either that, or mandatory life sentence for *any* life you take. I mean, why should you one day get to live your life as you please if you taken away someone else's ability to do so?
Change my view!