By contrast, in accordance with Justice Department rules, the FBI kept its investigation into the Trump campaign—which began in July—under wraps, including its surveillance of former Trump campaign adviser Carter Page, on whom the Nunes memo largely focuses. As a result, the FBI’s only public influence on the election worked to Trump’s advantage.

The history of the FBI shows how dangerous a politicized bureau can be. For decades under J. Edgar Hoover, the bureau treated the Constitution as a mere list of suggestions, tapping phones, breaking into homes, and suppressing political activists, particularly non-violent left-wing and civil-rights activists, because Hoover regarded them as domestic enemies. But the long list of political foes that Trump and his allies have said should be prosecuted suggests that they seek not to protect the bureau’s independence, but to turn it into a weapon to wield against their opposition. They are not opposed to politicizing law enforcement; they are demanding it be politicized.

The Nunes memo provides an illustrative example. The document focuses largely on a dossier compiled by the former British intelligence agent Christopher Steele on behalf of the firm Fusion GPS, whose account for opposition research on Trump’s Russia ties, first started by anti-Trump Republicans, had been taken on by the Democratic National Committee. The memo argues that the FBI’s application to the Foreign Intelligence Surveillance Court for an order to spy on Page, which cited the dossier, did not “disclose or reference the role of the DNC, Clinton campaign, or any party/campaign in funding Steele's efforts, even though the political origins of the Steele dossier were then known to senior and FBI officials.”

Nunes has since acknowledged publicly that the FBI did indeed include a footnote referencing Steele’s political leanings, but still maintains that the FBI abused its power by including information from a biased source—a claim legal experts say has little basis. Yet foreign-intelligence gathering often involves using information from sources with private or political agendas. FBI informants can themselves be unsavory characters: gangsters, terrorists, Nazis. From a legal standpoint, the question is what other information was in the application, and whether the underlying information cited in the dossier was accurate, and the Nunes memo makes no attempt to argue that it wasn’t. And given that the Nunes memo is itself a partisan document, written by Republicans in possible consultation with the White House and released by the committee on a party-line vote, it cannot be the case that Republicans believe that partisan sources cannot provide reliable information.

The Nunes memo, as my colleague David Graham wrote last week, largely refutes its own premise by acknowledging at the end of its four pages that the Russia investigation began with a Trump foreign-policy adviser, George Papadopoulos, seeking derogatory information on Clinton from Russian sources, months before the Page order was sought. But the fight over the Nunes memo also reveals the fundamental asymmetry of the current conflict over the FBI and its role in a democracy. Nunes and the president’s allies aren’t arguing that the FISA-warrant process is structurally flawed and that the court should have a more adversarial process, as civil libertarians have proposed. They aren’t calling for citizens subject to such surveillance to be able to challenge such warrants in court. They don’t want more restrictions on the ability of the government to eavesdrop on Americans communications without a warrant—in fact Nunes himself supported expanding such powers in January.