This is a bit of a mess of a question. And why are you leaning so heavily on Locke? Not that he was some sort of oracle (e.g. in regard to empiricism and the nature of knowledge), but much of what he wrote on this was in support of challenging authority.
It's been a while and I'm trying to sunbathe, but let me attempt to sum up how I read him: in regard to natural law, Locke's grounding of morality is ambiguous and, some argue, incoherent based on his empiricist works, but I think I would express it along the lines of God's commands are morally obligatory, and one can come to know them, with certainty, through reason. Law, then, is an extension of this and is binding by virtue of it being grounded in God.
In regard to government, then, legitimate government is limited and grounded in the consent of its citizens. When governments act against natural rights (stemming from natural law), one is justified in opposing them. Would you be a coward if you stole food from the state in order to distribute it more equitably among a starving population? Would you be a coward if you murdered a genocidal leader in order to prevent him from wiping out a percentage of his citizens? I doubt Locke would think so.
