On its face, the fact that 47 Senate Republicans wrote to Iran this week in the hopes of sabotaging international diplomacy is itself shocking. The very idea of American officials brazenly trying to undermine their own country’s foreign policy in the midst of delicate nuclear talks is simply breathtaking.

But what makes the stunt, spearheaded by Sen. Ton Cotton (R-Ark.), especially scandalous is how unusual it is. In the American tradition, elected U.S. officials have never actively and publicly tried to do their own freelance foreign policy in such a shameless and high-profile way.

Or have they? McClatchy dug a little deeper on the unprecedented nature of the GOP gambit.

The U.S. Senate Historian’s Office has so far been unable to find another example in the chamber’s history where one political party openly tried to deal with a foreign power against a presidential policy, as Republicans have attempted in their open letter to Iran this week. […] In the past, [Senate Historian Donald Ritchie] said, “what usually happened is a senator would sign a ‘round robin’ letter or a sense of the Senate resolution, or write a letter to the president or secretary of State voicing objections to some particular policy. Individual senators have also on occasion met with the foreign leaders on policy issues, Ritchie said. In this case, he said his office conducted a general search on disarmament issues to see if an episode similar to the Iran letter could be found.

Ritchie told McClatchy his office looked, but “really didn’t find anything.”

The same report quoted Alan K. Henrikson, director of Diplomatic Studies and a professor of diplomatic history at Tufts University, said this week marks a first: “Neither the Senate nor the House has sought to interfere with actual conduct of negotiations by writing an open letter to the leadership of a country with which the U.S. is negotiating.”

A Politico report added yesterday, “Experts say the Senate GOP’s Iran letter may be an unprecedented breach of foreign policy protocol both in its form and its boldness.”

There is, however, a specific example from 2007 that Republicans and some of their defenders say undercuts the point.

Towards the end of the Bush/Cheney era, then-House Speaker Nancy Pelosi (D-Calif.) traveled to Syria and met with Syrian leader Bashar al-Assad. Then-Vice President Dick Cheney complained to Rush Limbaugh at the time, “The president is the one who conducts foreign policy, not the speaker of the House.”

So, does this disprove the criticism of Cotton & Co.? Not really. For one thing, Pelosi notified both the White House and the State Department in advance of her trip. She also received a policy briefing from Bush administration officials about developments in Syria, and Pelosi was told that the staff at the U.S. embassy in Damascus would be available if needed.

In other words, Pelosi honored U.S. protocols and worked with the executive branch instead of trying to circumvent it. Let’s also not forget that the Bush administration was not actively involved in delicate negotiations with Syria at the time.

What’s more, the Democratic leader met with Assad in the hopes that engagement would be more productive than isolation, but Pelosi did not encourage the Syrian leader – or any other foreign officials – to ignore the Republican White House or distrust American foreign policy. [Update: see below.]

In other words, the parallels to this new scandal are tenuous, at best.

That said, at the time, congressional Republicans suggested Pelosi’s actions may have been illegal because the Logan Act “makes it a felony for any American ‘without authority of the United States’ to communicate with a foreign government to influence that government’s behavior on any disputes with the United States.”

By this same Republican definition, wouldn’t Cotton’s letter be a rather obvious example of violating federal law?

I realize that Republicans have actively tried to undermine U.S. foreign policy throughout the Obama era. Sen. Rand Paul (R-Ky.) traveled to Guatemala last year and worked against U.S. foreign policy during the migrant-children crisis. In 2010, then-House Minority Leader Eric Cantor (R-Va.) traveled to Israel in the hopes of undermining U.S. foreign policy in the Middle East. Actions like these used to be unheard of in the American tradition, but once President Obama took office, Republicans largely re-wrote the rules.

But none of these actions went quite as far as Tom Cotton and his 46 friends. The specific circumstances – the nature of the international talks, the ongoing diplomatic efforts, the deliberate attempt at sabotage – suggest this is very likely a controversy unlike any before it.