I'm definitely not the person to ask -- I don't particularly live in this space, and I'm fairly sure other people here do and could answer more completely, but:
If you see modern society in a democratic environment with the (somewhat naive) outlook that a large enough group of people have consented to be governed by the laws of the land, then it's really up to the law on when this is allowed/disallowed. It's more of a reflection of the people (or.. who's making the laws), and what they've decided -- if people decide that personal privacy is protected under law then so be it. If people decide police are allowed to break the law (at all) then so be it. If people decide that police are somehow above what would normally be a law when they have certain piece of paper (search warrant) signed by the local wiseman (judge) who is likely looking out for the best interests of the community and country at large, so be it.
Things get blurry really quickly, and this is a gross oversimplification of how any of these systems work, but it's how I tend to think about it. I sometimes think that it can't be any other way -- once a bunch of humans attempt to work together, there are some fundamental problems that just end up best solved this way (in terms of efficiency and other factors).
If you see modern society in a democratic environment with the (somewhat naive) outlook that a large enough group of people have consented to be governed by the laws of the land, then it's really up to the law on when this is allowed/disallowed. It's more of a reflection of the people (or.. who's making the laws), and what they've decided -- if people decide that personal privacy is protected under law then so be it. If people decide police are allowed to break the law (at all) then so be it. If people decide that police are somehow above what would normally be a law when they have certain piece of paper (search warrant) signed by the local wiseman (judge) who is likely looking out for the best interests of the community and country at large, so be it.
Things get blurry really quickly, and this is a gross oversimplification of how any of these systems work, but it's how I tend to think about it. I sometimes think that it can't be any other way -- once a bunch of humans attempt to work together, there are some fundamental problems that just end up best solved this way (in terms of efficiency and other factors).