When Donald Trump abruptly fired FBI Director James Comey, who was overseeing the investigation into Russia’s meddling in last year’s election, political observers were quick to denounce the move as a nearly unprecedented assault on the rule of law. Not since 1973—when Richard Nixon fired Archibald Cox, the special prosecutor looking into Watergate—had a president so obviously tried to shield himself from scrutiny. “We are careening ever closer to a constitutional crisis,” Senator Edward Markey warned shortly after the news broke.

But Comey is far from the only watchdog Trump has tried to silence. Since the day the president took office, he has quietly been waging war on inspectors general—the federal officials charged with ferreting out government waste, fraud, corruption, and mismanagement. In a startling break with tradition, Trump has rescinded the nominations of four inspectors put forward by Barack Obama without offering replacements, threatened to fire those already in office, dragged his feet on filling vacancies, and left a dozen key departments without a permanent watchdog in the top job. Some of the departments that are now operating without independent oversight—including the CIA, the NSA, Defense, and Interior—have harbored some of the biggest scandals in American history, from Teapot Dome to Abu Ghraib. “Trump is creating a politics of impunity,” says John Wonderlich, executive director of the Sunlight Foundation, a leading champion of government transparency.

Since the position of inspector general was created in 1978, shortly after Watergate, these investigators have ousted corrupt officials, protected government whistle-blowers, saved taxpayers billions, and kept Congress informed about what goes on behind closed doors in 73 federal agencies. It was the CIA’s inspector general who helped expose how the Bush administration was illegally torturing detainees being held without due process in “black sites” scattered around the world. The NSA’s inspector general, meanwhile, investigated George W. Bush’s unconstitutional program of warrantless wiretapping—an assault on civil liberties that only became public when the inspector’s report was leaked to the press in 2013. Inspectors general also serve as the frontline against government waste and fraud: Studies show that for every dollar invested in their offices, they save taxpayers $14.

“A dedicated and independent inspector general is an invaluable resource not only for the agency it serves or the Congress it reports to, but for the American people,” says Danielle Brian, executive director of the Project on Government Oversight, a nonprofit watchdog organization. “Often the unsung heroes, IGs are essential to a well-functioning federal government.”

Trump isn’t the first president to push back against the independence and power of the inspectors general. Jimmy Carter imposed several federal hiring freezes, which limited oversight work. Ronald Reagan, on his first day in office, summarily fired 16 inspectors general he inherited from his predecessor. (Two months later, however, he reinstated five and promised to nominate replacements for the rest quickly.) Barack Obama left inspector general seats vacant for months and even years on end, setting a dangerous precedent for Trump.

Under Obama, in fact, many offices were overseen by acting inspectors or deputies—underlings whose temporary status made them vulnerable to pressure from above. “They become politically cautious, afraid of sticking their neck out in any way that might be seen as controversial,” Brian says. “That creates a kind of chilling effect.” Had there been a permanent inspector general at the State Department, for example, Hillary Clinton might have been barred from using a private email server. But Obama left the position vacant for Clinton’s entire tenure.

What makes the situation even worse under Trump—beyond his inability to tolerate criticism of any sort—is his penchant for turning public institutions into private piggy banks for his friends and allies. At the Department of the Interior, for example, the president is working to open up wide swaths of federal land to drilling and mining. It falls to the department’s inspector general to police these government leases, ensuring that the energy industry doesn’t profit unduly at taxpayer expense. As recently as 2008, the inspector general at Interior discovered officials in the Minerals Management Service steering lucrative contracts to favored oil and gas companies, which showered them with gifts: free golf trips, lavish ski vacations, tickets to Colorado Rockies games. Government bureaucrats were buying and selling cocaine in the office; one official, while running the Denver office, allegedly coerced two female subordinates into having sex with him.

Back then, Interior had a permanent inspector general who uncovered the abuse and presented his findings to Congress. But today, even as Trump readies himself to hand out new government leases, the post has been sitting vacant for more than eight years. And the recent hiring freeze implemented by Trump has crippled the office even further. In March, the inspector general’s office warned the House Oversight Committee that greater oversight on everything from cybersecurity to fraud in oil and gas royalties is “simply not possible at our current levels.”

The CIA has also been operating without an inspector general for more than two years—another vacancy that could have far-reaching consequences. Without a top watchdog in place, for example, it would be far easier for Trump to make good on his promises to reinstate torture. (“Would I approve waterboarding?” he told a cheering crowd on the campaign trail. “You bet your ass I would, in a heartbeat.”) To make matters worse, the president has repeatedly threatened to prosecute leakers who reveal damning information about his administration, making it less likely that government employees will come forward to report wrongdoing in the first place—especially in the intelligence agencies, where there are few avenues for protected disclosures. “When there aren’t safe channels for whistle-blowers internally, they end up going public,” says Brian. “Edward Snowden is the perfect example of that phenomenon.”

If the government were fully staffed with inspectors general, Trump himself would likely come under even greater scrutiny. Democrats in Congress have already asked the current inspectors general to look into the president’s threats against whistle-blowers, as well as his overseas business holdings and the government lease he was granted to turn the Old Post Office Pavilion on Pennsylvania Avenue into Trump International Hotel. Representative Rosa DeLauro, a Democrat from Connecticut, has even called for a new inspector general to be installed within the White House. “We have never seen such a level of collusion and corruption in the highest levels of our government,” DeLauro said recently. “Not even with Watergate in the Nixon administration or the Teapot Dome scandal in the Harding administration.”

Arthur Schlesinger, the Harvard historian, observed that major scandals wash over Washington every 50 years. The last was in 1973, when Watergate shattered the public’s trust in the executive branch. If the pattern Schlesinger identified holds, the next wave of corruption is fast approaching, and Trump’s undermining of the inspectors general will only hasten its arrival. “The Trump administration has created an environment that demonstrates that they don’t really care about ethics,” says Wonderlich. “And as we all know from experience, this is the kind of environment where waste and corruption flourish.”