Despite many strident complaints about the need to protect “sources and methods,” the president and his defenders in Congress are right to try to bring to light the details of the counter-intelligence investigation of the 2016 Trump campaign. 

Keeping sources and methods secret is a sound general principle. The intelligence and law enforcement communities cannot protect the country if their tools and assets are publicly exposed. Accordingly, the mere curiosity of the public, or even of high-ranking members of Congress, does not justify attempts to reveal how our security and law enforcement services do their work or where they are getting their information.

Things look considerably different, however, when someone is being accused of serious wrongdoing on the basis of such information. This is the case now, as many have suggested that President Trump has some kind of compromising relationship with one of America’s foreign rivals. After all, he has long been under investigation for “Russian collusion.” In the face of such grave accusations, the justification for keeping sources of information secret becomes very much weaker.

This would be most clear if there were ever to be a criminal proceeding against the president. As they show daily by their heated rhetoric, Donald Trump’s most furious detractors actually hope to see him prosecuted for misdeeds they suppose him to have committed. If this were to happen, it would become difficult to protect the sources of the information used against him. On the contrary, he would have a constitutional right under the Confrontation Clause of the Sixth Amendment to examine the evidence against him and to confront and question the government’s witnesses. 

To be sure, the law provides procedures whereby classified sources and methods can be protected while the defendant is given access to information necessary to an adequate defense. Nevertheless, in a trial of such monumental political interest there would be tremendous pressure to reveal as much as possible, and it would be impossible for a witness to testify without disclosing his identity to the president if he were a defendant.

Of course, not all of the president’s opponents are panting for a prosecution. Some of them merely hope to see him impeached by the House of Representatives and perhaps removed from office by the Senate. In such a matter, the president would have no formal right to examine the origins of all the evidence presented against him. As a matter of raw power, the required majorities in Congress (a simple majority in the House to impeach, a two-thirds majority of the Senators present to remove) have considerable leeway to decide what information is sufficiently convincing that the president is guilty of “high Crimes and Misdemeanors.” 

Nevertheless, if an impeachment were to happen, there would be strong and justified political pressure to bring out all of the relevant information and to expose its origins. The president’s defenders would demand it, and his opponents would be in no position to refuse. The impeachment of a president is among the most deeply consequential acts that any Congress can undertake. Presumably even the president’s most brazen political enemies would hesitate to vote against him in such a proceeding while telling the public that the basis for their belief in his guilt has to remain to some extent cloaked in secrecy. 

This brings us to the less inflamed, but no less determined, of the president’s political enemies: those who merely wish to use the investigation to damage him politically. Here there are no formal rules, and in the rough-and-tumble of partisan politics many people do and say whatever they think they can get away with. There are, however, informal rules of decency and prudence that weigh heavily against making claims of “Russian collusion” while at the same time opposing the president’s desire to reveal the origins of such claims.

The idea that the president of the United States is the tool of a foreign power is, or ought to be, absolutely shocking. No president has ever been seriously suspected of such a thing. Those who traffic in such ideas or insinuations ought, in common decency, concede the right of their target to demand to know how such a suspicion could arise. Many people hate Donald Trump, and he may have earned their hatred by his combativeness and ruthlessness. Yet even the people we hate have a right to defend themselves against charges that necessarily involve the deepest disgrace that can befall a public figure.

Prudence, too, calls for a full accounting of the origins of the “Russia collusion” accusation. It is America’s boast to be a self-governing nation. The charge of a president’s collusion with a foreign power goes to the heart of the people’s ability to trust the institutions that serve them, and hence of their ability to be truly self-governing. They therefore have a right to know — or, to put it more strongly, the public good requires that they should know — everything relevant to judging such a charge.

If the president is guilty of improper collusion with a foreign power, it is imperative that the people be truly convinced of it by seeing all the evidence. And if the president is not guilty of it, it is equally imperative that the people see the weakness or absence of evidence, so that corrosive doubts about the country’s institutions may be dispelled. These considerations are more compelling than protecting intelligence “sources and methods,” as important as that is in more ordinary circumstances.