S.H.I.E.L.D. is not an American institution answerable to American laws, expectations or conventions.
They told Ian that he had no rights.
If he literally had zero rights, then they would have been allowed to torture and murder him, which is why May wasn't in any trouble for beating Quinn, which is an extension of the Bus being an Embassy, although they'd have more freedom if the bus was declared international waters (space?) and then no laws applied on that plane, or any other S.H.I.E.L.D. installation in the world other than S.H.I.E.L.D. internal policy.
What radius past the Busses hull extends this law void?
a hundred meters?
2 miles?
200 miles?
That's how the international says it works. Plant a flag in an unclaimed territory and 200 miles in every direction of that flag belongs to you.
The trouble of course is that these days everything is claimed except international waters, so you're building a derrick or a pontoon island if you want to start a kingdom.
Has anyone tied claiming that Garbage Vortex and building on it?
http://en.wikipedia.org/wiki/Great_Pacific_garbage_patch