A hotly anticipated inspector general report about then-FBI Director James Comey’s handling of the Hillary Clinton email investigation is finally complete. It was released publicly Thursday afternoon — and is guaranteed to become a lightning rod in President Trump’s clashes with his own Justice Department.

The report contradicts President Trump’s often-expressed belief that the investigation was rigged to get Clinton off the hook. Justice Department inspector general Michael Horowitz found little affirmative evidence on the whole that political bias affected officials’ handling of the probe itself. (You can read the full text at this link.)

Indeed, FBI director Christopher Wray — appointed by Trump to replace Comey last year — said at a Thursday afternoon press conference that “this report did not find any evidence of political bias or improper considerations actually impacting the investigation under review.”

However, Horowitz was far more critical on two specific fronts.

First, Horowitz writes, FBI officials involved in the case sent each other messages on their FBI devices “that created the appearance” of political bias. Here he particularly criticizes FBI counterintelligence agent Peter Strzok for texting his co-worker and lover, Lisa Page, that “we’ll stop” Trump from winning the election.

Horowitz says he found no affirmative evidence that Strzok skewed his decision-making for political reasons. But he says he “did not have confidence” that Strzok’s decision in the campaign’s final month to prioritize the Trump campaign/Russia probe over new Clinton emails on Anthony Weiner’s laptop “was free from bias.” He writes that Strzok and other FBI employees “brought discredit to themselves” and hurt the bureau’s reputation.

Second, Horowitz sharply criticizes then-FBI director James Comey for his public statements about the Clinton email case — specifically, his July 2016 decision to publicly announce that he wouldn’t recommend any charges, and then his October 2016 decision to tell Congress about that new emails had been found.

Horowitz concluded that while Comey didn‘t act out of political bias, he “usurped the authority of the Attorney General,” “chose to deviate” from established procedures, and engaged “in his own subjective, ad hoc decisionmaking.” He writes that the Clinton email case was indeed extremely unusual — but that established procedures “are most important to follow when the stakes are the highest.”

But even though Horowitz’s report largely isn’t about the Russia investigation, it’s being released in a political context dominated by both Mueller’s probe and Trump’s attacks on his Justice Department. Indeed, Trump has recently signaled that he’s eagerly anticipating the IG report, since it was expected to criticize Comey, and he is trying to undermine Comey’s credibility.

What is taking so long with the Inspector General’s Report on Crooked Hillary and Slippery James Comey. Numerous delays. Hope Report is not being changed and made weaker! There are so many horrible things to tell, the public has the right to know. Transparency! — Donald J. Trump (@realDonaldTrump) June 5, 2018

Still, Horowitz’s criticisms cut in different political directions. Those particular FBI agents’ private leanings were anti-Trump, while Comey’s public statements ended up hurting Clinton. But to understand the new report, you have to understand who Michael Horowitz is, and what, exactly, he’s supposed to do.

What is an inspector general?

Often called the “watchdog” for the federal government, an inspector general is supposed to investigate allegations of misconduct within his or her particular agency. Each major Cabinet department has one, and so do various other federal offices and agencies — there are 73 inspectors general (or IGs) in total. (This helpful CRS report lists them all.)

When inspector general offices were first established in the mid-1970s, their primary task was to investigate “waste, fraud, and abuse” in federal spending, and that remains an important part of their job today.

But gradually, their authority has expanded to the point where IGs have become all-purpose scandal investigators. It’s become understood that when something controversial goes down at an agency, it’s the IG — who’s outside the normal chain of command — that’s supposed to look into it. IGs can start investigations based on whistleblower complaints, referrals from their office’s leadership, or requests from Congress.

A department’s IG has the authority to examine relevant records from the department, from memos to emails. IGs have subpoena power and can arrange interviews of current employees — interviews in which it would be a crime to make false statements. So their investigations have the potential to be quite vigorous.

Yet one crucial thing to understand is that inspectors general have no authority to actually charge anyone with crimes (or indeed, to impose any disciplinary actions). Their investigations end when they assemble reports on what they found. These reports, which are generally made public, can recommend that people be prosecuted, but actual charging decisions are left to elsewhere in the Justice Department.

The most prominent IGs are all presidential appointees who have to be confirmed by the Senate. However, the offices do have a reputation for independence. Though the president can fire them so long as he tells Congress why in advance, in recent decades that’s rarely been done. Instead, IGs are generally (though not always) left in place and get to serve until they choose to move on.

Trump has so far abided by that tradition. Nearly all of the most prominent inspectors general are still holdovers from the Obama or even George W. Bush administrations. They include the IGs for State, Treasury, Defense, Health and Human Services, the Environmental Protection Agency, Veterans Affairs — and Justice Department Inspector General Michael Horowitz.

Who is Michael Horowitz?

By now, Trump has cleared out most of the Justice Department’s Obama-era leadership — but Inspector General Michael Horowitz remains.

Horowitz has deep roots in the department. From 1991 to 1999, he worked as an assistant US attorney in Justice’s prestigious Southern District of New York office, where he led a major investigation into police corruption. He was then promoted to higher-level roles in the main Justice Department’s criminal division — first as deputy assistant attorney general and then as the division chief of staff. In 2002, he left the government and spent the next decade as a partner at the law firm Cadwalader, Wickersham & Taft (where he was well-compensated).

When the Justice Department’s well-respected Inspector General Glenn Fine decided to resign after a decade in the post, President Obama decided to nominate Horowitz to replace him. With congressional Republicans already demanding various investigations into the Obama administration, Horowitz was likely picked because he was a nonpartisan figure who’d worked under presidents of both parties. The Senate confirmed him without objection in the spring of 2012.

Horowitz has served in the post in the six years since. In that time, he’s overseen investigations into politically charged matters like “Fast and Furious,” the mishandled operation to infiltrate a weapons-smuggling ring in which law enforcement officials allowed hundreds of weapons to be smuggled into Mexico. (Horowitz’s report criticized 14 officials for mishandling the matter.)

He’s occasionally clashed with Justice and FBI leadership, publicly criticizing them for failing to turn over records on grand jury investigations relevant to his probes. And he’s become a sort of champion for the IGs themselves, chairing a council of inspectors general and asking Congress to give IGs more investigative powers.

Overall, Horowitz is viewed as a vigorous investigator who takes his job quite seriously. He generally isn’t believed to have political motivations — his only known donation is to Sen. Michael Bennet (D-CO) in 2010. “Straight shooter” is one of the most common phrases used to describe him. But now he’s been tasked with his most hot-button investigation yet.

What is this IG report about?

On January 12, 2017 — after Trump had won the election but before his inauguration — Horowitz announced that he was opening “a review of allegations regarding certain actions” by the Justice Department and FBI “in advance of the 2016 election.”

By that, he meant, mainly, officials’ handling of the now-closed Hillary Clinton email probe, and not the probe of the Trump campaign’s ties to Russia. (The latter investigation hadn’t even been publicly confirmed to exist at the time and is still ongoing even today.)

To recap the infamous chain of events in the Clinton probe: When it emerged in 2015 that Clinton had used a personal email account on a private server for all of her emails while she was secretary of state, the Justice Department launched an investigation into whether she had mishandled classified information. Eventually, in a decision Comey says was unanimous among his investigative team, the FBI privately concluded that it wouldn’t recommend any charges in the matter.

But by the summer of 2016, the case had become enormously politically charged, with GOP nominee-in-waiting Donald Trump repeatedly claiming the investigation would result in Clinton’s indictment. And after word leaked out that Attorney General Loretta Lynch and Bill Clinton had met on an airport tarmac in late June, Republicans claimed the fix was in.

So on July 5, 2016, Comey bypassed Justice Department leadership to make a highly unusual public statement in which he announced that though he believed Clinton had been “extremely careless” in her email practices, he would not recommend any charges in the case. Republicans blasted him for his conclusion that charges weren’t necessary, while some Democrats questioned why he felt compelled to pontificate publicly about a probe in which he found no criminal wrongdoing.

Comey’s public statements about the case continued, first in extensive congressional testimony, then in an October 28 letter announcing the FBI had discovered new emails that could be relevant, and then in another November 6 letter saying the new emails didn’t change the FBI’s investigative conclusion. All this was highly unusual, to say the least, and some analysts believe Comey‘s late letters helped swing the election to Trump.

Horowitz’s January 2017 announcement suggested he’d examine criticisms of Comey‘s behavior from all sides of the political spectrum — and certain other officials’ conduct too. These included then-Deputy FBI Director Andrew McCabe (who some conservatives said should have recused himself because Clinton ally Gov. Terry McAuliffe had earlier helped fundraise for McCabe’s wife’s failed state Senate campaign), and then-Justice official Peter Kadzik, who had contacts with Clinton campaign chair John Podesta. Finally, Horowitz also said he would look into DOJ and FBI leaks that happened during the campaign more generally.

What did the IG report find?

Overall, Horowitz finds little affirmative evidence that political bias affected the FBI‘s handling of the Hillary Clinton email investigation — but he criticizes political bias from certain employees, particularly counterintelligence agent Peter Strzok. And he criticizes Comey for deviating from established procedure.

Regarding the overall handling of the email probe itself, Horowitz extensively reviewed decisions about who the FBI and DOJ interviewed, how they sought evidence, how they decided to grant immunity to certain people, and so on. Without endorsing all these choices, he concluded that overall they were “not unreasonable” and seemed based on investigative judgment calls — not political bias, as Trump and many on the right have often asserted.

Yet on two more specific fronts, Horowitz is far more critical.

First, Horowitz writes, FBI officials involved in the case sent each other messages on their FBI devices “that created the appearance” of political bias. Here he particularly criticizes FBI counterintelligence agent Peter Strzok for texting his co-worker and lover, Lisa Page, that “we’ll stop” Trump from winning the election.

Horowitz says he found no affirmative evidence that Strzok skewed his decision-making for political reasons. But he says he “did not have confidence” that Strzok’s decision in the campaign’s final month to prioritize the Trump campaign/Russia probe over new Clinton emails on Anthony Weiner’s laptop “was free from bias.” He writes that Strzok and other FBI employees “brought discredit to themselves” and hurt the bureau’s reputation.

Second, Horowitz sharply criticizes then-FBI director James Comey for his public statements about the Clinton email case — specifically, his July 2016 decision to publicly announce that he wouldn’t recommend any charges, and then his October 2016 decision to tell Congress about that new emails had been found.

Horowitz concluded that while Comey didn‘t act out of political bias, he “usurped the authority of the Attorney General,” “chose to deviate” from established procedures, and engaged “in his own subjective, ad hoc decisionmaking.” He writes that the Clinton email case was indeed extremely unusual — but that established procedures “are most important to follow when the stakes are the highest.”

So the IG’s two biggest criticisms cut in different political directions. Those particular FBI agents’ private leanings were anti-Trump, while Comey’s public statements ended up hurting Clinton.

What does all this mean for the Russia investigation?

Inevitably, and almost regardless of the report’s specifics, President Trump will attempt to exploit it to try and discredit the Russia investigation (even though, again, this IG report is largely not about the Russia investigation).

It’s not the first time Trump has tried to use the Clinton email case against Comey. Back when Trump fired him as FBI director in May 2017, the White House initially put out a cover story saying he did so because Comey violated DOJ policy in the Clinton email probe.

This was self-evidently absurd, because the DOJ memo criticized Comey for actions that hurt Clinton (his critical public statement about her, and his late letter saying new emails had been found). Trump, meanwhile, had long made it unmistakably clear that he thought Comey was too easy on Clinton in 2016 — and he ended up torpedoing his aides’ story by admitting the Russia probe played a role in his decision just two days later.

But now the new IG report could prove useful to Trump for a few different reasons, as Mueller investigates whether Trump obstructed justice by firing Comey.

For one, Comey is an important witness to Mueller, and several of his key interactions with Trump occurred without anyone else present. Trump, naturally, has aimed a barrage of criticism at the fired FBI director in an attempt to impugn his credibility as a witness, calling him “a leaker and a liar.”

Trump is also searching for ways to argue that he was correct in firing Comey, and that that act did not constitute obstruction of justice. So if the IG concludes that Comey mishandled the Clinton email case, Trump will likely question how firing an FBI director who’d made such major errors could possibly be construed as obstruction. (However, many legal experts believe that if Trump fired Comey with corrupt intent, in hopes of thwarting an investigation he viewed as dangerous for either himself or his allies, it could still be obstruction.)

The IG report is also being released in the midst of a continuing effort by Trump to try to undermine the Justice Department’s independence and discredit the Mueller probe more generally as part of a “deep state” plot against him. So the more Horowitz criticizes the Obama-era Justice Department leadership, the more ammunition Trump will have against them too.

Horowitz, though, is likely trying to ignore this larger political battle by focusing only on his particular role — to assess whether there was any Justice Department misconduct with regards to the 2016 election. Perhaps, in the end, that’s all he can be expected to do.