“For some months representatives of the FBI and of the Department of Justice have been formulating a plan of action for an emergency situation,” the FBI Director briefed the White House, “wherein it would be necessary to apprehend and detain persons who are potentially dangerous to the internal security of the country.” Something called a “master warrant” would suffice to round up the detainees, in a crisis, following a suspension of habeas corpus. The detention centers were supposed to be military bases near New York, San Francisco and Los Angeles. “A statement of charges [would] be served on each detainee and a hearing [would] be afforded the individual,” the director continued, although that procedure “would not be bound by the rules of evidence.”

That was not something that happened after 9/11. That was a briefing prepared by J. Edgar Hoover, the paranoid maniac who molded the FBI in his image, for President Truman in 1950. Hoover actually began concocting his plans for mass detention of subversives — he would call them “terrorists” — two years earlier, not “some months” earlier. But presidents only needed to know these things when Hoover felt they needed to know these things.

Among the most valuable contributions of Tim Weiner’s excellent forthcoming book, Enemies: A History of The FBI, is the methodical demonstration that warrantless domestic spying and military detentions are not the result of uncharted policy territory fostered on the Bush and Obama administrations by the 9/11 Era. The widespread domestic spying, at least, has been the FBI’s stock and trade since the 1930s — the detentions a persistent fantasy of Hoover’s starting around then — and very rarely bounded by law. If these are issues that concern you, I strongly advise you to buy this book. It’s insane that Weiner could follow up what I consider the best book ever written on the CIA with such a rich counterpart about the FBI.

The history of the CIA is a history of the abuse of power without commensurate gains in national security. (To skip forward a couple decades, Weiner spits venom at Louis Freeh for birddogging Bill Clinton’s trysts while al-Qaida was leaving a trail of clues that it was preparing to attack the United States.) When laws didn’t establish the FBI’s authorities, Hoover’s orders were to spy on Americans — break into their homes, take their possessions — and not to get caught. When courts made it clear the FBI’s rampant illegality would poison prosecutions, Hoover smiled a condescending grin, since prosecutions weren’t the point of his “intelligence gathering.” The point was achieving the desired result: a mobilized FBI, with Hoover at the helm, thwarting threats to national security — real, exaggerated and imagined.

The most salient case in point: A team of four German saboteurs arrived on Long Island by submarine in June 1942, with another sub of four arriving separately in Florida. The sub’s leader, George Dasch, quickly had second thoughts about his mission, and turned himself in to the FBI on June 18, providing sufficient information for the bureau to roll up all eight would-be Nazi saboteurs. (They included two U.S. citizens.)

Hoover informed Franklin Delano Roosevelt four days later. Except he chose not to mention that Dasch turned himself in and confessed everything. The way it sounded, the FBI rounded up an active wartime threat through good sleuthing. Roosevelt immediately ordered the creation of a secret military commission. Within days, the commission found all defendants guilty; electrocuted the six non-citizens; Dasch got 30 years; the other U.S. citizen got his death sentence commuted to life.

Inevitably, the Supreme Court had to decide the question of whether any of this was legal — an obviously extraordinary thing, because for six of the eight defendants, there could be no remedy even if the Court ruled it wasn’t. “But the proceedings had been so secret that no record was presented to the Court,” Weiner recounts. Ultimately the Court ruled that the government had the power to try defendants as unlawful enemy combatants. But Chief Justice Harlan Fiske Stone wrote that the Court “could not define with meticulous care the ultimate boundaries of the jurisdiction of military tribunals to try persons according to the laws of war.”

The ruling became known as Ex Parte Quirin. It would become a significant part of the Bush administration’s legal basis for military commissions and indefinite detention. And it started from a basic FBI deception.

When I read Weiner’s peerless book about the CIA, Legacy of Ashes, it made me more appreciative of the basic dilemma at the heart of the agency. The CIA is the guy holding the bag for the dirty business presidents wish to commit. It is very rarely a rogue agency. Weiner’s account of the FBI paints the opposite portrait. For most of its existence, it has been a lawless, unaccountable organization, contemptuous of any outside democratic control, dismissive of the liberties it trampled, and providing dubious benefit to national security. And the decisions it made during its most reckless years hang over our heads today like a stormcloud.