With Robert Mueller’s probe of Russian electoral interference finally complete—even though the public is still waiting to learn what it says—many Republicans are declaring it’s time to pivot back to investigating the investigators. Sen. Lindsay Graham, an erstwhile Trump critic who has reinvented himself as one of the president’s fiercest defenders, has announced his intent to lead the charge, with particular focus on whether the FBI abused the Foreign Intelligence Surveillance Act to wiretap former Trump advisor Carter Page. Trump himself has vowed to release a more complete version of the FISA applications targeting Page (already public in heavily redacted form), along with related documents

“The FISA warrant issued against [former Trump advisor] Carter Page, based on a dossier prepared by Christopher Steele, is at a minimum disturbing,” said Graham last week, echoing a claim first championed by former House Intelligence Committee Chair Devin Nunes in a now-notorious memorandum. “Whether or not it’s illegal, I don’t yet know. So I’m going to get answers to this.”

I’ve written before that I find little merit in the arguments raised by Nunes, and the portrait they paint of a politically-motivated Deep State conspiracy to bring down Trump—are without merit. That assessment still stands. But what little we’ve learned about Mueller’s findings does suggest there are aspects of the FBI’s surveillance of Page that deserve further scrutiny. They’re just not the aspects Graham and his co-partisans are most agitated about.

One of the two concrete findings from the Mueller report made public thus far, in a letter by Attorney General William Barr, is that Mueller’s “investigation did not establish that members of the Trump Campaign conspired or coordinated with the Russian government in its election interference activities.” Presumably that extends to Page, who briefly served as a foreign policy advisor to the Trump campaign. On face, that would seem to imply that the evidence before Mueller was insufficient to demonstrate that Page was an “agent of a foreign power,” as the FBI had asserted to the FISA court in seeking its surveillance order.

If that’s true, it wouldn’t necessarily mean the FBI acted improperly in obtaining that initial order. Sometimes intelligence agencies follow leads based on information from sources they assess to be reliable, and that information turns out to be wrong. We know, for example, that only a very tiny fraction of the “assessments” the FBI opens each year blossom into full-blown investigations, but it’s impossible to know how many of those full-blown investigations similarly come up empty. FISA orders, unlike criminal wiretap warrants, are designed to gather intelligence, and not intended to lead to criminal prosecution in most cases. Even when they do, the government is typically reluctant to introduce FISA intercepts in court if they can make a case with other evidence. That means there’s no good way to evaluate the success of intelligence investigations by looking at prosecution statistics. Moreover, the public statistics on FISA orders, do not distinguish between new orders and extensions, which means there’s no good way to even approximately gauge how commonly FISA wiretaps are abandoned as dead ends.

Yet in Carter Page’s case, the FBI clearly did not believe they had hit a dead end. A FISA warrant targeting a United States person must be renewed every 90 days, as Page’s was on three separate occasions, by three different FISA Court judges. Those renewal applications would not merely have recited the evidence supporting the initial order: They would have been expected to describe the fruits of previous surveillance, and justify continued monitoring by showing that useful intelligence was being gathered—or, at the very least, that there was good reason to expect some in the future.

Though almost all of the new information added to the renewal applications remains redacted, the length of the applications increased substantially over time: The initial submission the the FISC totaled 66 pages, while the final renewal application had grown to 101 pages. While presumably not all of the additional 35 pages concerned the information gleaned from wiretapping Page, some significant portion must have. So what was the FBI telling the FISC to justify continuing surveillance? And how do we square that with Mueller’s inability to establish coordination between Trump associates and Russia? It is unfortunate, but probably inevitable, that the government will sometimes target people for surveillance and discover that their suspicions were mistaken. If, however, the government conducts nine months of intrusive electronic surveillance, persuades a court that their suspicions have been confirmed, and still proves to have been wrong, that is at least a prima facie indication of something wrong with the system.

The trouble for those wedded to the idea of an anti-Trump Deep State conspiracy is, precisely, that it suggests something wrong with the system. A vendetta against Trump does little to explain why investigators would continue spying on Page well into 2017, long after he’d left the campaign and Trump had been sworn in as president, nor why Trump appointee Rod Rosenstein would sign off on that final renewal application. If Page had never been a foreign agent after all, then the fact that Republican officials signed off on those applications, and FISC judges—all chosen by Supreme Court Chief Justice John Roberts—approved them, would instead raise troubling questions about the larger process designed to oversee and check intelligence wiretaps. Yet relatively few of the Republican lawmakers expressing concern about potential FISA abuse have shown any interest in reforming the broader framework of intelligence surveillance—preferring to focus on the purported misconduct of a handful of supposed bad apples.

There are, of course, ways Mueller’s conclusion could conceivably be reconciled with the protracted surveillance of Page. Perhaps he was indeed acting as a Russian agent in some capacity, but not privy to their election interference campaign. Russia might, for instance, wish to gather information about the new administration, or exert influence on it, and it would have no reason to make its assets privy to any of the details of its information operations.

At this point, however, the government should have to either explain why its continued monitoring of Page was justified, or admit that it made a grave error—which should prompt a searching review of how the error continued as long as it did, and why the system of FISA oversight failed to put a halt to it sooner. While many details will doubtless need to remain secret—either for security reasons or to protect the privacy of Page and his associates—the considerations typically invoked to rationalize categorical secrecy no longer apply. The world already knows Page was wiretapped, and those he spoke to will already assume their conversations were intercepted. There may yet be reason not to divulge, for instance, precisely which communications channels the government is able to access and which it cannot, but with so much information is already in the public domain, the overall calculus of interests should shift significantly in the direction of further disclosure.

Perhaps that disclosure will, one way or another, restore public confidence that the system is functioning properly. Perhaps it will support the view that, whether through malice or genuine error, something went badly awry in this specific investigation. And perhaps it will raise alarming questions about the FISA system as a whole, and whether it effectively protects Americans against unjustified intrusions into their most intimate communications. Either way, it’s time to kick the tires.