Many who favor the use of torture -- er, enhanced interrogation techniques -- on those suspected of terrorism attempt to bolster their arguments by claiming that it's ok because, universal conceptions of human rights be damned, the Constitution only applies to U.S. citizens.
To put it simply, they're very, very wrong. Glenn Greenwald explains this well in a new piece:
[In a 2009 Supreme Court decision,] none of the 9 Justices -- and, indeed, not even the Bush administration -- argued that the Constitution applies only to American citizens. That is such an inane, false, discredited proposition that no responsible person would ever make that claim....It is indisputable, well-settled Constitutional law that the Constitution restricts the actions of the Government with respect to both American citizens and foreigners. It's not even within the realm of mainstream legal debate to deny that.
However, despite the recency of this example, this is hardly a new idea made up by a modern, activist SCOTUS. Greenwald notes that the exact same opinion was part of SC jurisprudence in the late 1800s. And even a cursory examination of the text of the Constitution itself -- which clearly distinguishes between "persons" (meaning everyone, regardless of citizenship) and "citizens" -- shows that it was never the intention of the founders to apply the guarantees of the Constition only to those boasting American citizenship.