I can agree with what Over said but at the same time, right or wrong, social networks are considered public. Now when I say public I also speak of places like BC for example. Anyone and I mean anyone can look at anything posted here at this website. There is no expectation of privacy and in the case of law enforcement or in the case of the employer too, anyone can see what is said just as if someone were talking loud in a crowded elevator.
Facebook however "may" be a different animal on one ground. If on Facebook you don't want other than approved friends to see what you said, then are you speaking loud in the crowded elevator? There is some, albeit limited, expectation to privacy so does this grant law enforcement authority to breech this firewall and look at what you posted regardless of probable cause? Notice I didn't say they never could but that probable cause must exist!
Ok now go the next step and should law enforcement be able to breech your home computer firewall and look on your hard drive? Obtain your passwords and breech the firewalls of your bank account or investment accounts? What about your UPSers.com account? All in the name of the public good!
Police and even public officials are by no means immune from human temptation and the fact of the matter is, history is loaded and loaded with horror stories of human authority and power gone very badly arye. The same fallible people who make up the public, from which bad people come from is also the same source from which police and public officials are choosen so there you go. That being the case, how far do we extend them carte blanche in their duties and the more important question, should checks and balances be in place? Why have a checks and balance on the President or why on Congress?
Should a measure of benefit of doubt or innocent until "proven guilty" by fact (not media story or gut feeling) be the standard? Do we in effect, kill all the innocent bystanders on the street but claim victory because we got the bad guy too? The bad guy got justice, true enough but where is the justice for the innocent who just got caught up in the crossfire? Does justice and moral right have a limit when it comes to the greater public good?
Life will never, ever be without risk and until we realize this, those who claim they can eliminate all risk and make us all safe will be able to manipulate and twist us to their advantage and enrich themselves in power or wealth or both as a result. I'll always error on the side of risk because I know a life without any risk is a lie!
