> what leads you to Iran is the stance "if it's legal then it's OK".Nope. What I said is that, if it's legal then it's OK from a legal perspective, which is a tautology really and I can't believe I'm still explaining it to you.
> "But separation of powers!" is an Iran-like answer to this
To the contrary, the Iranian answer is to implicate moral into everything so that the law has to answer to "superior values", and to be honest I struggle to understand how you could fail to see this (unless you don't really know how Iran runs -- hint: religious/moral authority trumps regular law).
Separation of powers starts with the "two swords" of religious and temporal power being handled in different ways by different people, back when these topics were first seriously discussed in Europe (one could argue that the "unto Caesar" line is the start of this particular debate, but it was basically ignored for centuries afterwards). When people realized that this separation alone was not enough of a guarantee, they split it further (roughly along Montesquieu's lines) exactly so that nobody could inflict its own personal moral code on the whole of the community without the community agreeing first. When the community changes its stance (because of moral or technical changes or whatever), then it collectively agrees that laws should change, and new law supersedes old law. This is how the system should work in a democratic society (which is not to say that's actually what happens, but it's the ideal we strive for, so to speak).
Law shouldn't answer to anything but future law. The US Constitution lives about most other laws, but it's still "just" law.
That is how progress is achieved and how we can all live together without starting religious wars every other day.