If you want to be more accurate I'll take republic instead of democracy although both terms are correct here in the US. 
Don't get me wrong, I love LEOs. There were several places in town I wouldn't have gone in without one when I was still working EMS. However, when I'm asked to stop taking photographs of something that I have every right to photograph I'm not just going to say "yes sir" and move on. LEOs need to know the limits of their power and when they're going to cross into the realm of violating constitutional rights. As I was once told by an officer; "Ignorance of the law is not an excuse" -- that applies to LEOs as well.
If you're taking photos of a crime scene and you're on public land (or your own, or your neighbors...), not endangering or interfering, and outside the incident circle then the officers on scene need to get back to business and leave you alone - it isn't a hard concept to grasp or follow.
edited to add:
I would like to take a moment to say that almost all LEOs I've spoken with over these types of issues realized and respected my rights after a brief and polite discussion. Now security guards and similar (like MBTA officers here in MA) are another matter.