Actually, I was reading the bill of rights just the other day in a debate raging on a big national blog to which I comment. It occurs to me after reading it that we actually don't have the right to know. What we have is an "interest in" so that we can vote appropriately.
It all comes down to the vote - not the right. We have recourse to inquire and the government is, within reason, duty and legally bound to respond. They have to tell us if we ask except in cases where disclosure would be detrimental to the common welfare.
Laws are put in place to fill in the cracks when the inquiry is in doubt; laws the limit the government's ability to dodge disclosure and operate in secret and laws that say to the citizens "no means no and if you are unsuccessful in persuading a court (checks and balances) then you can't just break into something and get the information just because you have an interest in it.
People who think that Wiki-leaks did a public service are just flat out wrong. An interest about is not a right.