Last week’s IG report about the FBI made a big splash. Here’s what you need to know about inspectors general.

This past Thursday, Department of Justice Inspector General Michael Horowitz released a much-anticipated report about how the FBI and Department of Justice investigated Hillary Clinton’s use of a private email server. To put it mildly, this got a lot of media attention.

We won’t add to that. But in case you were wondering exactly what an inspector general is and does, here are some answers.

1. We can (mostly) thank Watergate for creating IGs

Congress created IGs in the 1970s, as it was trying to shore up government integrity after the Watergate revelations and scandals in the federal bureaucracy. The original Inspector General Act established an Office of the Inspector General (OIG) — led by a single inspector general — in each of the 12 Cabinet-level departments.

Presidents appoint IGs “without regard to political affiliation,” subject to Senate confirmation. IGs technically serve at the pleasure of the president. Notably, President Ronald Reagan faced a strong public backlash after firing all the IGs appointed by his predecessor, Jimmy Carter. However, since then, new presidents have generally left IGs in place.

The 1978 law excluded all national security-related departments, including the Department of Justice. Only after protracted battles in Congress over IG access to sensitive security-related records were IGs also appointed to investigate the State, Justice, Defense, Treasury and Homeland Security departments. Today, the federal bureaucracy has 73 IG offices, although that includes some weaker ones appointed by agency heads themselves.

2. The IGs’ roles have evolved over time

Congress originally directed IGs to eradicate fraud and waste in the departments. Initially IGs limited their attention to routine mismanagement and petty fraud. Their primary tool kit included audits, investigations, inspections and evaluations — some routine, others undertaken at the request of Congress or members of their host department. The IGs could initiate proceedings in the Justice Department, issue subpoenas and investigate.

During the 1990s, two developments transformed and enhanced the role of IGs. First, the Reinventing Government movement, a set of bureaucratic revisions spearheaded by Vice President Al Gore, pushed IGs to be more like in-house management consultants, recommending ways to make the bureaucracy more effective and efficient.

Second, IGs experimented with new forms of investigations, the most important of which was created by Justice Department IGs, known as a “Special Investigation.” IGs can’t force compliance with their recommendations, since their suggestions are not legally binding and IGs cannot bring criminal charges. Nor can IGs compel disciplinary sanctions. Instead, these probes provide “narratives” or accountings that explain to Congress and the public what went wrong and what further actions should be taken.

3. Independence is a balancing act

A former IG once described his role as “straddling a barbed wire fence.” IG reports are addressed to a number of principals: their host departments, congressional oversight committees, the Office of Management and Budget and even the media. Competing loyalties and incentives help to preserve IGs’ independence by preventing any single overseer from co-opting them. Indeed, the 1978 law stipulated that IG reports would be sent directly to Congress as well as to the department head, to make sure their findings weren’t quietly quashed. Their independence also depends on having adequate resources to carry out investigations, which varies over time and IG offices.

To protect IGs from being politicized, Congress over time has given IGs more resources, enshrined their law enforcement authority into law, and expanded their access to records inside and outside their host departments. In 2016, after the Justice Department tried to curb IG authority, Congress passed reforms protecting all IGs’ right to “full and prompt access” to all agency records.

4. How to judge IG success: by outcomes, not outputs

IG reports seem to have no teeth. Their recommendations are not legally binding, and hundreds of their recommendations go unheeded each year. So evaluating their offices’ success by measuring outputs like funds recovered or waste avoided is the wrong approach.

Instead, it’s best to judge IG success by the narratives of events they produce. These sorts of public accounting enable other political actors — elected officials, journalists and citizens — to begin holding government accountable. In an age of fake news and widespread distrust in political institutions, IGs can establish a common truth by establishing facts and placing events in bureaucratic and political context. Their success varies, but countless IG reports have prompted significant agency reforms, prosecutions and policy changes.

5. Even without teeth, IG reports can matter

President Barack Obama appointed Horowitz, the Justice Department IG. Like his predecessors, however, Horowitz regularly pursues investigations that incriminate actors of all parties, including the administration that appointed him. In keeping with that tradition, Thursday’s IG report gave fodder to both President Trump’s and Clinton’s supporters: The report found that while political bias did not unduly affect the handling of Clinton’s emails, anti-Trump sentiment was alive and well within the FBI. Both camps extolled the report as evidence for their side.

In cases like the investigations of former FBI director James B. Comey and Clinton, there is an important difference between wrongdoing and breaking the law. IG reports can detail the niceties of administrative discretion in ways that might not be possible in a law enforcement investigation. Horowitz’s report subtly distinguishes among lawbreaking, poor but “not unreasonable” decision-making, failing to follow standard procedures, and political bias.

This is hardly consolation for either side. But Horowitz’s report gives a common reference for Democrats and Republicans and a starting point for drawing judgments about FBI and Justice decisions during the campaign.

As long as politicians protect IGs’ independence, IGs can promote bureaucratic neutrality and deliver contextualized facts, as free of political judgment as possible. This is the first step toward public accountability. It’s up to politics to do the rest.

Nadia Hilliard will be a lecturer (assistant professor) in U.S. Studies at the Institute of the Americas, University College London, beginning in September.