Usually, the intelligence agencies do warantless wiretapping behind closed doors on people they know to be criminals. They at least try to cover it up and pretend to obey the constitution. Bush blatantly disobeyed the constitution and blatantly spied on his own people. Obama attacked this policy yet continued it. Of course, it's not like the federal government seizing new powers in violation of the constitution is anything new either. Lincoln suspended habeas corpus.