My former diplomatic colleagues Bill Taylor and George Kent were put in a very unfamiliar, uncomfortable position on Capitol Hill on Wednesday. In contrast to their day jobs promoting American interests overseas, often through discrete conversations, Taylor, the top U.S. diplomat in Ukraine, and Kent, the deputy assistant secretary of state for Europe, were asked to publicly testify against an administration and a president they continue to serve.

Fundamentally, their role — and the role of the many diplomatic officials slated to appear at the high-profile congressional hearings to determine whether President Donald Trump should be impeached — is to help define what constitutes the legitimate practice of diplomacy and whether the president crossed the line into making demands for personal or political favors.

Part of the problem with Trump’s requested favor is there are a lot of other pressing favors our country needed from Ukraine to promote regional security.

I’d like to clear up some confusion. There are regular things that U.S. emissaries do that involve “quid pro quos” or “conditions.” The Trump administration alternately denies using such leverage with Ukraine or claims their actions were in keeping with normal diplomatic practices. The most important difference, though, is that when diplomats do so, it is for the benefit of our national security, not the president’s political security. And in fact, when there are signs that things are amiss, there are mechanisms in place for those same diplomats to act — with no need for (or history of) the president getting involved.

Let’s start with the centerpiece of the impeachment inquiry: Trump’s request that Ukrainian President Volodymyr Zelenskiy investigate Hunter Biden, the son of a key 2020 political rival, former Vice President Joe Biden, on allegations of corrupt activity while he was on the board of the Ukrainian energy company Burisma. Coinciding with that request was the holdup of aid to Ukraine and the scheduling of a White House visit, both of which Zelenskiy desperately sought.

So, let’s talk about the pros and cons of quid pro quos. Diplomacy is definitely all about working out reasonable exchanges. But, kind of like asking a nosy neighbor to borrow some butter, those asks are made quite selectively and carefully. When you make such a request, you’re always acutely aware that they can turn around and justifiably make a similar demand themselves. That’s normally why the National Security Council runs through a long list of options to separate the really important ones from those that are only sort of important. Part of the problem with Trump’s requested favor is there are a lot of other pressing favors our country needed from Ukraine to promote regional security and American interests.

What tends to top that list as a worthy condition for a White House visit? At the Obama White House, where I worked, we would ask for military support in places like Afghanistan or peacekeeping operations. I remember that one colorful Latin American head of state’s visit to the Oval Office took place only after he agreed to take several former Guantanamo detainees. Often invitations to visit Washington would simply be put off until we saw an improvement in human rights, democracy and the rule of law in those countries.

Once there’s a consensus about what to ask for, whether for a White House visit to be set or for U.S. aid to flow, there’s also a protocol for who does the asking. To start with, the president needs to avoid making certain requests for legal reasons. If it's not lawful to do in our own country, why the heck should we be encouraging it in other countries? Despite Trump’s best efforts, the White House cannot demand an investigation by the Justice Department, and therefore he can’t demand an investigation by a foreign nation.

Furthermore, there are already plenty of diplomatic channels in place when help from foreign countries is needed for investigations connected to the United States. In fact, it’s a primary duty of our embassies, which is why the FBI has what’s called a legal attache in place in Kyiv and many other capitals.

And there’s more we can do besides merely appealing to foreign countries for help. We have something called the Foreign Corrupt Practices Act. As diplomats, we are all too familiar with this law, as we encounter violations fairly frequently. It’s actually perfect for just the kind of nefarious foreign dealings that Trump, Rudy Giulliani his personal attorney, and their merry men wanted to find. Basically, the law says that if an American citizen is engaged in corruption overseas, they can be tried in the United States.

Boom. No need to ask for special presidential favors or arm-twisting in the murky world of Ukrainian politics. We can handle it all back here at home. Trump’s team could simply present the evidence they collected to the FBI, who would build a case and then swiftly bring charges.

This law is a cornerstone of U.S. efforts to pursue cases of corruption, a priority Republicans often point to as being a core motivation for Trump holding up aid to Ukraine. So it’s puzzling that Trump has called the Foreign Corrupt Practices Act “a horrible law” that puts American companies at an unfair disadvantage overseas and has worked to weaken its provisions. And whatever his GOP allies say, apart from allegations against the Bidens, such illegal activity does not seem to be an urgent concern for the president; this year he again moved to slash the budget for combating international corruption.

Here’s another reason why a president going over his diplomats’ heads isn’t kosher: It can have devastating effects on the countries themselves. Imagine if Franklin D. Roosevelt had telephoned Winston Churchill in 1941 and said: “I know we promised to come to your defense, but first I’m going to need you to do me a favor. Look into some crazy allegations I’ve heard about Thomas Dewey. My personal attorney will tell you more.” In Ukraine, soldiers were dying and citizens were living under daily danger while the $250 million in aid was delayed.

It also worsens the positions of our diplomats when the executive branch of government should be strengthening them. Secretary of State Mike Pompeo has refused to publicly defend them. Giulliani is running around claiming to speak for the president to Ukrainian officials. This isn’t just unorthodox, it’s deeply unsettling and downright dangerous for our designated representatives abroad.

The question before Congress is whether to believe a group of people who were entrusted with some of the most important positions in our national security structure.

This isn’t ultimately about what a whistleblower said or saw. Two veteran American ambassadors on Wednesday described their significant struggles with the situation on the ground in Kyiv. Officials from the departments of State and Defense, numerous members of the National Security Council and an adviser to the vice president all recounted their difficulties and discomfort with the process they saw unfold. Their testimony has been remarkably consistent. At the end of the day, the question before Congress is whether to believe a group of people who were entrusted with some of the most important positions in our national security structure.

Sure, Trump came into office promising to toss out the old playbook. Our diplomats dutifully adjusted to the torrent of tweets and tariffs. Yet what we will see in the coming days is evidence of an administration that didn’t just change the working of diplomacy, but violated it by repeatedly and recklessly trying to circumvent the law and our fundamental values.

Despite their considerable concerns, Taylor and his colleagues never asked to testify. They followed the diplomatic rulebook, raising questions and issues internally. Yet when called on to tell the truth, they have honored their oath to the Constitution. That isn’t a deep state conspiracy; it’s a deep and abiding commitment to our country, for which all Americans should be grateful.