The Commerce Clause
Critics of the federal government like to ascribe its ballooning power in criminal cases to the fear-driven actions of recent Republican administrations. A longer view, however, reveals that the government's actions that breed discontent in 2008 were made possible by the overreaching of a Democratic administration more than seventy years ago. Like today, we had a president in 1937 who was eager to expand the power of the federal government - then in the name of the New Deal, now for the sake of the Global War on Terror.
Luckily for FDR, he won the 1936 election by a landslide and was able to threaten to pack the Supreme Court, which had been overturning the New Deal; following this threat the Court turned around and broadened the federal government's Commerce Clause power with the National Labor Relations Board v. Jones & Laughlin Steel Corporation decision in 1937.
It is beyond cavil that the power of the federal government took a great leap forward with Jones & Laughlin Steel. Perhaps you think that this was a bad thing. You must nevertheless admire the Hamiltonian brilliance of a court that, at a stroke, converted a weak federal system to an almost all-powerful centralized government that held sway without serious challenge for almost sixty years (until U.S. v. Lopez, which held in 1995 that it's not necessarily the federal government's business when I carry my six-shooter in a school zone).
Government's omnipresence in our lives can mostly be blamed on the Commerce Clause jurisprudence from 1937 on - if FDR hadn't successfully seized jurisdiction over everything touching interstate commerce, we would have no war on drugs; we would also likely have had no Civil Rights Act. In other words, without Roosevelt's threat to pack the court, federal government would be a shadow of its current self.
Apparently the Commerce Clause cannot be read too broadly to satisfy men like George W. Bush, who has presided over the greatest growth in federal government ever. Nevertheless, the Government's successful Commerce Clause power grab is not entirely the fault of the neocons or even of the Republicans; it can be blamed, instead, on government's natural imperative to attain more power.