Much has been made of Donald Trump’s latest promise not to run as a third party candidate – a specter that has haunted Republican operatives ever since Trump started surging in the polls this summer.

The curious thing is that anyone believes him this time.

Trump already made this exact pledge – that he wouldn’t run as a third party candidate – to the Republican National Committee this fall. He even signed a piece of paper saying as much to much fanfare and with cameras rolling. “I will be totally pledging my allegiance to the Republican party and the conservative principles for which it stands”, he told the crowd that day.

He also said that he wouldn’t rip up the written pledge at a later date.

It all may sound like a case of protesting too much, but they’re actually important qualifiers for a guy whose platform consists of tearing up trade deals that he doesn’t like.

Then, of course, after giving his word to America, he repeatedly went and tore up the pledge. Not literally, mind you – but he threatened repeatedly to disregard the substance of the thing he made such a circus over honoring.

Just a month after he made his much-touted initial pledge, after rumors surfaced that Republicans were coordinating a takedown of his candidacy, he told ABC News of the pledge: “I will see what happens. I have to be treated fairly.”

Then, when the GOP establishment reacted less than warmly to his – racist and likely unconstitutional – suggestion that we ban all Muslims from immigrating to the United States, Trump made noises about taking back his pledge. The chair of New Hampshire’s Republican Party, for instance, dubbed Trump’s call to ban all Muslims from entering the country: “Un-Republican, unconstitutional and un-American.” Such great betrayals from Republican standard-bearers this month had Trump tweeting: “A new poll indicates that 68% of my supporters would vote for me if I departed the GOP & ran as an independent.”

One doesn’t have to parse the language too finely to read between those lines.

If “I’ll see what happens” is all that a signed document with a high-profile rollout gets the RNC, why does anyone think for a moment that Trump would be bound by a toss-away comment in a forgettable debate?

The first time a gentleman gives his word is supposed to be enough, but apparently the rules are different for Trump – and they always have been.

A better guide to Trump’s behavior than his word might be what’s actually legal under election law.

It is very tough to run as a third party candidate, election law expert Rick Hasen tells me, and it’s even harder for someone in Trump’s position – which is to say, someone who’s already running as a Republican. Just to get ballot access if you’re running as an independent means fighting your way there state-by-state, an expensive and time consuming task.

And as a candidate who’s already filed as a candidate in the Republican primaries, Trump would face additional legal obstacles. Some state laws make it illegal to run either as an independent or as the candidate of another minor party (like the Libertarian or Green parties) having been a candidate for the Republican nomination.

Those laws – known as sore-loser laws – received media attention recently when the Ohio secretary of state announced that, because Trump is currently a Republican candidate, he would be ineligible to run later as an independent in the state. “It’s not clear if these laws are constitutional,” Hasen, a University of California-Irvine professor who also runs a popular election law blog, explained. “But it’s another hurdle and it would require litigation in places like Ohio.”

But it’s litigation that Richard Winger, editor of Ballot Access News, thinks that Trump could win.

Parties get to determine who’s on their ballot in a primary – but the general election is a different story: parties don’t have a right of refusal over candidates outside their party. “Sore loser laws do not apply to presidential primaries except in three states,” Winger told me – Texas, South Dakota and Ohio. “And there’s ways around it in those three states.”

Specifically, Winger said, Trump could do something like have his son run in the general election as a proxy, instructing supporters to vote for the younger Trump. Such moves would be extremely irregular but not unprecedented. In 1966, for instance, George Wallace was constitutionally prohibited from running for re-election as governor of Alabama and so his wife ran and won. He was seen as the power behind the throne.

Not that Winger believes it will come to that – but there’s a long tradition of candidates pulling a switcheroo after losing a primary fight and running against their own party.

Illinois Republican John Anderson decided to run as an independent candidate in the 1980 presidential election after it became clear that Ronald Reagan was going to win the nomination. And in what should be construed as a warning sign for Trump naysayers: he succeeded in getting on the ballot in every single state.

More recently, perennial presidential candidate Lyndon LaRouche has switched parties multiple times following Democratic presidential primary losses. The last time was in 1992, when he decided to run as an independent in the general election after officially running for the Democratic Party nomination. Another perennial candidate, Gary Johnson, was on the Republican presidential primary ballot in eight states ahead of the 2012 presidential election, but in December 2011 announced that he was going to seek the libertarian nomination instead. He got on the ballot in 48 states.

More importantly, the pledge Trump took to the RNC has no force of law – “It legally means nothing,” Winger noted – and the RNC’s only recourse would be to try to shame Trump publicly. (That hasn’t worked well for critics in the past.)

Whatever Trump does, Republicans who think this latest assurance will bind Trump to anything are dreaming. If his candidacy has taught us anything, it’s that nothing can tie Trump down – not even Trump himself.