It is technically illegal for the government to torture prisoners. Almost no one would deny that. Section 2340 of the federal criminal code makes it a crime punishable by up to 20 years to “inflict severe physical or mental pain and suffering” on anyone in custody. Common Article 3 of the Third Geneva Convention—which like all ratified treaties has the force of law under the Constitution—likewise prohibits the “mutilation, cruel treatment and torture” or the “humiliating or degrading treatment” of captives. But the government can still go ahead and torture prisoners without any legal consequence, because neither of those laws can be enforced.
The Executive Branch has tried to use the national secrets ploy more often to cover up its own misdeeds than to actually protect national security. And it pretty much does not matter which political party is in party. It is as though the perks of the office transcend politics.
As long as there is no way to enforce laws against torture, then our Executive Branch can continue doing something illegal. Because, as Nixon said, When the President does it, that means that it is not illegal.